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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
101

How participatory methods facilitate social learning in natural resource management. An exploration of group interaction using interdisciplinary syntheses and agent-based modeling

Scholz, Geeske 07 January 2016 (has links)
In this thesis, the central interest is to better understand how participatory methods applied during participatory processes in natural resources management can serve as nuclei for social learning. Thereby, the main focus is on learning via interaction in groups. My approach begins with the aim of developing an analytical framework which reflects the main processes that are effective within participatory methods. The framework presents an analytical tool, including proposed methods to monitor and compare the results of participatory approaches with respect to social learning. Building upon this framework, I develop an agent-based model to simulate and explore group dynamics. This model is intended to support a theoretical exploration of whether or not and if so, at what stage, personal views of a problem evolve into a shared understanding of a problem (which can be seen as a key element of social learning), and an assessment of how individual mental models and group properties relate to each other. Results of the model are interpreted to offer suggestions about factors hindering or fostering social learning during the application of participatory methods.
102

Dynamiques des prairies de montagne : intégration de la plasticité phénotypique dans un nouveau modèle à base d'agents / Mountain grasslands dynamics : integrating phenotypic plasticity in a new agent-based model

Viguier, Clément 27 November 2018 (has links)
Les prairies de montagne offrent de nombreux services ecosystémiques qui sont menacés par le changement global. Les traits fonctionnels constituent un outil prometteur pour caractériser les réponses des communautés à des changements de conditions environnementales et leurs répercussions sur les services associés. Cependant, des résulats de plus en plus nombreuses soulignent l’importance de la variabilité intra-spécifique des traits a également été mise en évidence. Pour étudier ces effets, je propose un nouveau modèle à base d’agents, MountGrass, qui combine la modélisation de communautés végétales riches en espèces avec des processus de plasticité phénotypique. Ces deux éléments au coeur du modèle sont associés grâce à des compromis d’allocation basés sur des patrons empiriques établis de stratégies d’utilisation des resources.Avec MountGrass, j’ai exploré l’impact de la plasticité phénotypique sur la croissance individuelle et les propriétés principales des communautés prairiales. À l’échelle individuelle, le modèle paramétré a révélé un fort impact positif de la plasticité phénotypique sur la croissance mais aussi sur la niche fondamentaledes espèces. Des phénomènes de convergence et de réduction de la sensibilité aux variations de conditionsexpliquent ces effets. À l’échelle des communautés, les simulations ont confirmé de forts effets de la plasticité sur la structure des communautés et leur diversité spécifique. Ces effets sont expliqués par l’effet combiné de la réduction du filtre abiotique et de la réduction des différences de compétitivité. Cependant, aucun effet majeur sur la stratégie dominante ou la productivité n’a pu être mis en évidence.Des implémentations alternatives ou des extensions du modèle devraient permettre de tester la robustesse des résultats obtenus et d’analyser d’autres schémas de dynamiques des communautés. En conclusion, ce travail ouvre la voie à une meilleure considération et une meilleure compréhension du rôle des variabilités intra-spécifiques dans les dynamiques des communautés végétales. / Mountain grasslands provide numerous ecosystem services that are likely to be impacted by global change. Plant functional traits hold great promise to succinctly characterise plant community response to changing environmental conditions and its effect on associated services; with growing evidence of the importance of intra-specific trait variability. I propose here a novel agent-based model, MountGrass, that combines the modelling of species rich grassland communities with phenotypic plasticity. These two key components are integrated via allocation trade-offs based on established empirical patterns of strategic differentiation in resource-use.With MountGrass, I explored the impact of phenotypic plasticity on individual plant growth and on main properties of grassland communities. At the individual level, the parametrised model revealed a strong impact of plasticity on growth and species’ fundamental niches, with potentially large impacts on community properties. These effects are explained by the convergence of species’ strategies and the reduction of the sensitivity to variable conditions. At the community level, simulations confirmed the strong effect of plastic allocation on community structure and species richness. These effects are driven by the cumulative effect of a reduction of both abiotic filtering and fitness differences between species. However, no clear effect on the dominant strategy or productivity could be detected.Going further, the robustness of these findings and other patterns of community dynamics should be analysed with alternative or extended implementations of MountGrass. In sum, this work opens a door towards a better integration and understanding of the role of the intra-specific variability in complex plant community dynamics.
103

Towards simulating the emergence of environmentally responsible behavior among natural resource users : an integration of complex systems theory, machine learning and geographic information science

Harati Asl, Saeed 12 1900 (has links)
La gouvernance pour le développement durable comporte de nombreux défis. L'un de ces défis consiste à mieux comprendre les systèmes socio-écologiques gouvernés. Dans de tels systèmes, l'apprentissage par essais et erreurs implique le risque de conséquences inattendues, irréversibles et néfastes. De plus, en raison de la complexité des systèmes socio-écologiques, les leçons tirées d'expériences à petite échelle ne peuvent pas toujours être applicables à des problèmes à grande échelle. Un autre aspect difficile des problèmes de développement durable est que ces problèmes sont souvent multidisciplinaires et composés de composants qui sont chacun étudiés individuellement dans une discipline différente, mais il existe peu d'informations sur leur comportement ensemble. Un troisième défi de la gouvernance pour le développement durable est qu'il est souvent nécessaire d'impliquer les parties prenantes dans des actions de gestion et des mesures d'intervention coûteuses pour les individus qui y participent. De plus, dans de nombreuses situations de ce type, les incitations financières et l'application des réglementations se soldent par un échec et ne constituent donc pas des options de gouvernance. Dans cette thèse, les défis ci-dessus sont abordés dans un exemple de contrôle des perturbations forestières avec une approche intégrée. Pour éviter le problème des effets indésirables irréversibles et pour permettre des expériences répétées, une approche de simulation est utilisée. Pour relever le défi de la multidisciplinarité des problèmes des systèmes socio-écologiques, deux modèles sont développés indépendamment - portant sur les aspects sociaux et écologiques du système de l'étude - et ils sont ensuite couplés de telle sorte que la sortie de chaque modèle est utilisée comme entrée pour l'autre modèle. Pour résoudre le problème de l'engagement des parties prenantes, un plan est proposé pour la promotion d'un comportement respectueux de l'environnement. Ce plan est basé sur l'offre de reconnaissance à ceux qui adoptent volontairement le comportement responsable. Le modèle écologique de cette étude, qui simule la propagation d'une perturbation forestière, est construit à l'aide de l’apprentissage automatique supervisé. Le modèle social de cette étude, qui simule l'émergence d'une nouvelle norme de comportement, est construit à l'aide de l'apprentissage par renforcement. Les deux modèles sont testés et validés avant couplage. Le modèle couplé est ensuite utilisé comme un laboratoire virtuel, où plusieurs expériences sont réalisées dans un cadre hypothétique et selon différents scénarios. Chacune de ces expériences est une simulation. A travers ces simulations, cette étude montre qu'avec un algorithme de prise de décision approprié et avec suffisamment de temps pour l'interaction entre une entité gouvernante et la société, il est possible de créer une motivation pour un comportement responsable dans la société. En d'autres termes, il est possible d'encourager la participation volontaire des acteurs à l'action pour le développement durable, sans que l'entité gouvernante ait besoin d'utiliser des incitations financières ou d'imposer son autorité. Ces résultats peuvent être applicables à d'autres contextes où un comportement responsable des individus ou des entreprises est recherché afin d'atténuer l'impact d'une perturbation, de protéger une ressource écologique, ou de faciliter une transition sectorielle vers la durabilité. / Governance for sustainable development involves many challenges. One of those challenges is to gain insight about the social-ecological systems being governned. In such systems, learning by trial and error involve the risk of unexpected, irreversible and adverse consequences. Moreover, due to complexity of social-ecological systems, lessons learned from small scale experiments may not be applicable in large-scale problems. Another challenging aspect of problems of sustainable development is that these problems are often multidisciplinary and comprised of components that are each studied individually in a different discipline, but little information exists about their behavior together as a whole. A third challenge in governance for sustainable development is that often it is necessary to involve stakeholders in management actions and intervention measures that are costly for individuals who participate in them. Moreover, in many of these situations financial incentives or enforcement of regulations result in failure, and are thus not options for governance. In this thesis, the above challenges are addressed in an example case of forest disturbance control with an integrated approach. To avoid the problem of irreversible adverse effects and to allow repeated experiments, a simulation approach is used. To tackle the challenge of multidisciplinarity of problems of social-ecological systems, two models are independently developed – pertaining to social and ecological aspects of the system of the study – and they are subsequently coupled in such a way that the output of each model served as an input for the other. To address the problem of engagement of stakeholders, a scheme is proposed for promotion of environmentally responsible behavior. This scheme is based on offering recognition to those who voluntarily perform the responsible behavior. The ecological model of this study, which simulates the spread of a forest disturbance, is built using Supervised Machine Learning. The social model of this study, which simulates the emergence of a new norm of behavior, is built using Reinforcement Learning. Both models are tested and validated before coupling. The coupled model is then used as a virtual laboratory, where several experiments are performed in a hypothetical setting and under various scenarios. Each such experiment is a simulation. Through these simulations, this study shows that with an appropriate decision-making algorithm and with sufficient time for interaction between a governing entity and the society, it is possible to create motivation for responsible behavior in the society. In other words, it is possible to encourage voluntary participation of stakeholders in action for sustainable development, without the need for the governing entity to use financial incentives or impose its authority. These results may be applicable to other contexts where responsible behavior by individuals or enterprises is sought in order to mitigate the impact of a disturbance, protect an ecological resource, or facilitate a sectoral transition towards sustainability.
104

Nonparametric upscaling of bark beetle infestations and management from plot to landscape level by combining individual-based with Markov chain models

Pietzsch, Bruno Walter, Wudel, Chris, Berger, Uta 04 June 2024 (has links)
Linked to climate change, drivers such as increased temperatures and decreased water availability affect forest health in complex ways by simultaneously weakening tree vitality and promoting insect pest activity. One major beneficiary of climate-induced changes is the European spruce bark beetle (Ips typographus). To improve the mechanistic understanding of climate change impacts on long-term beetle infestation risks, individual-based simulation models (IBM) such as the bark beetle dispersion model IPS-SPREADS have been proven as effective tools. However, the computational costs of IBMs limit their spatial scale of application. While these tools are best suitable to simulate bark beetle dynamics on the plot level, upscaling the process to larger areas is challenging. The larger spatial scale is, nevertheless, often required to support the selection of adequate management intervention. Here, we introduce a novel two-step approach to address this challenge: (1) we use the IPS-SPREADS model to simulate the bark beetle dispersal at a local scale by dividing the research area into 250 × 250 m grid cells; and (2) we then apply a metamodel framework to upscale the results to the landscape level. The metamodel is based on Markov chains derived from the infestation probabilities of IPS-SPREADS results and extended by considering neighbor interaction and spruce dieback of each focal cell. We validated the metamodel by comparing its predictions with infestations observed in 2017 and 2018 in the Saxon Switzerland national park, Germany, and tested sanitation felling as a measure to prevent potential further outbreaks in the region. Validation showed an improvement in predictions by introducing the model extension of beetle spreading from one cell to another. The metamodel forecasts indicated an increase in the risk of infestation for adjacent forest areas. In case of a beetle mass outbreak, sanitation felling intensities of 80 percent and above seem to mitigate further outbreak progression.
105

<b>Agent-Based Modeling Of </b><b>Infectious Disease Dynamics: Insights into Tuberculosis, Pediatric HIV, and Tuberculosis-HIV Coinfection</b>

Alexis Lynn Hoerter (18424443) 23 April 2024 (has links)
<p dir="ltr">Tuberculosis (TB), caused by <i>Mycobacterium tuberculosis</i> (<i>Mtb</i>), and human immunodeficiency virus-1 (HIV) are major public health concerns, individually and in combination. The status of the host immune system, previous <i>Mtb</i> infection and HIV-mediated T cell exhaustion, can have significant impacts on immune dynamics during reinfection. Individuals with asymptomatic latent TB infection (LTBI) may be protected against <i>Mtb </i>reinfection, as demonstrated by animal and <i>in vitro </i>studies. However, the underlying dynamics and protective mechanisms of LTBI are poorly understood. In HIV, long-term infection in children and associated T cell exhaustion leads to weakened immune responses to HIV reinfection. The complexity of these infections, particularly in the context of the heightened vulnerability of HIV+ individuals to TB, underscores the need for novel investigative approaches to study host-pathogen and pathogen-pathogen interactions. To this, we have developed an agent-based model (ABM) as a mechanistic computational tool to simulate the immune response to <i>Mtb </i>and HIV, separately and during coinfection. Our ABM integrates clinical and experimental data; simulates immune cell dynamics between macrophages, CD4+ and CD8+ T cells; and produces emergent granuloma-like structures – a critical response to <i>Mtb</i>. This <i>in silico</i> approach allows us to efficiently explore host-pathogen interactions and their clinical implications. By unraveling the complex interplay of immune cell activation, T cell exhaustion, and pathogen dynamics, our model offers insights that could guide the development of targeted therapies. By quantifying the multifaceted nature of these diseases and their interactions, we highlight the potential of computational approaches in understanding and treating complex diseases, individually and in combination.</p>
106

<b>A MULTISCALE MODEL TO STUDY ATP-INDUCED CALCIUM SIGNALING IN LARVAL ZEBRAFISH TAILFIN WOUND RESPONSE</b>

Mothieshwar Jayaraman Krishnan (19250446) 29 July 2024 (has links)
<p dir="ltr">Wound healing is a complex biological process orchestrated by intricate cellular and biochemical interactions. This study leverages a multiscale modeling approach, integrating agent-based and ordinary differential equation (ODE) methods within CompuCell3D, to investigate wound detection and calcium signaling in juvenile zebrafish. Calcium as a ubiquitous secondary messenger plays a crucial role in translating wound stimuli into cellular responses. We focus on the initial phase of wound detection, a multi-step process beginning at the subcellular level with the release of Damage-Associated Molecular Patterns (DAMPs) and subsequent calcium signaling. We hypothesize that an ATP diffusion wave acts as the primary trigger, initiating a downstream calcium signaling cascade mediated by inositol triphosphate (IP3). Calcium and IP3 production and movement from the injured cells to healthy ones would then coordinate a tightly regulated wound response. To investigate this hypothesis, we adapted existing equations from a Drosophila wing disc injury model. We carefully modified them to accurately represent the zebrafish system in our in-silico setup, specifically focusing on relevant agonists. Model predictions were rigorously compared to the zebrafish’s experimental data to validate the computational approach. Our findings provide preliminary evidence suggesting that ATP diffusion through the interstitial spaces of injured tissue may be a potent agonist, triggering localized calcium release closely resembling experimental observations. This multiscale modeling framework offers a promising avenue for significant advancements in wound healing research. It has the potential to facilitate the development of novel therapeutic strategies and discoveries by enabling the integration of cell signaling pathways and tissue engineering.</p>
107

Essays on choices, beliefs and adaptive behavior

Kühne, Regina 02 February 2015 (has links)
Diese Dissertation umfasst drei Aufsätzen, die sich mit Erwartungen, Entscheidungen und deren Rückwirkung auf die Umgebung beschäftigen. Der erste Aufsatz untersucht die Binnenwanderung von Ost- nach Westdeutschland. Dabei wird der Zusammenhang von Variation in ökonomischen Disparitäten zwischen der Ursprungs- und der Zielregion und Bildungsniveau, Alter und Arbeitsmarktstatus der wandernden Bevölkerung untersucht. Mit Hilfe der SOEP Daten von 1993 bis 2011 gelangt die Untersuchung zu dem Ergebnis, dass regionale Disparitäten in Verbindung mit der Selbstselektion der Wandernden stehen. Während die Wandernden im Durchschnitt jünger und besser ausgebildet als die Bleibenden sind, verringert sich dieser Unterschied, wenn die Differentiale in den Arbeitslosenquoten zwischen den Regionen steigen. Im zweiten Aufsatz entwickle ich ein Modell zur Untersuchung von prosozialem Verhalten in Begegnungen mit Fremden. Durch das Abstrahieren von Möglichkeiten der Reputationsbildung oder des Bestraftwerdens, entfallen die wesentlichen strategischen Motive für prosoziales Verhalten. Die Entscheidung prosozial zu Handeln ist dann nicht mehr strategisch vorteilhaft sondern intrinsisch motiviert durch Altruismus und einer Neigung sich an das Verhalten anderer anzupassen. In einem zweiten Schritt untersuche ich, ob die Erkenntnisse des Modells mit dem empirisch beobachteten Verhalten übereinstimmen. Der dritte Aufsatz skizziert eine (mögliche) Verhaltensstruktur und notwendige Bedingungen auf Mikroebene, die zu den beobachteten Verhaltensunterschieden in prosozialem Verhalten zwischen dem ländlichen und städtischen Raum führen. Den Rahmen des hier entwickelten Modells bildet das bekannte Gefangenen Dilemma, das wiederholt mit zufällig zugeordneten Partnern einer großen Gesellschaft gespielt wird. Das Modell bezieht Merkmale ein, die sich häufig in realen Begegnungen wiederfinden: imperfekte Information, freiwillige Teilnahme und eine Neigung sich dem Verhalten anderer anzupassen. / This thesis consists of three essays that analyze choices and beliefs to explore how both lead to adaptive behavior. The first essay examines the positive net migration flow from the eastern to western parts of Germany. The migration decision is substantially based on expectations about future developments. With economic conditions changing substantially over the past 20 years in the eastern part of Germany, the incentives to migrate have also altered, so changing the composition of the east-to-west migrant body. This essay explores variations in economic disparities between the region of origin and region of destination, relating them to changes in the skill level, age and labor force status of the migrant population. Analyzing SOEP data from 1993-2011, the findings suggest that, with falling wage differentials, older migrants are less frequent job-to-job movers and are more likely to be non-working prior to migration. Furthermore, while migrants tend to be younger and better educated than stayers, the group of movers becomes partly less distinct from the group of stayers with respect to the skill and age composition when regional disparities in employment opportunities increase. The second and the third essay of this thesis model the decision making process in social interactions between strangers. In these situations, choices are often affected by beliefs about others behavior. In the second essay of this work, I develop a simple model of prosocial behavior for encounters between strangers. By abstracting from the possibility of reputation building and punishment between anonymous partners, I remove the main strategic motives for prosocial behavior so reducing it to a simple non-strategic decision. The principal motivation to behave prosocially is then intrinsic, based on altruism, with a taste for conforming to the behavior of others. In this way, individual decisions are conditional on the behavior of others. Emerging equilibria will then explain the occurrence of prosocial or cooperative behavior within a given society. In a second step, I analyze whether the model’s predictions are consistent with the empirical evidence on the link between beliefs and prosocial behavior using data on blood donations. The third essay outline a (possible) micro-structure and conditions which lead to the observed urban-rural differences in cooperative behavior using agent-based modeling. The model presented here adapts the familiar framework of a prisoners dilemma which is played repeatedly with randomly matched members of a large population. I introduce features that are often found in real world interactions: imperfect information, voluntary participation and a taste for conforming to majority behavior. In this analysis, peoples beliefs about the level of cooperation in the population and their resulting behavior are determined endogenously. Both are governed principally by the experience that they derive from interactions. I present results of an agentbased simulation in order to study the emerging dynamic relationships, to examine how cooperative behavior evolves over time under different circumstances, and to determine how urban-rural differences in behavior emerge. The factors that give rise to rural-urban differences are heterogeneity in individual loss aversion or risk taking, and limited migration possibilities between rural and urban areas.
108

A modeling perspective on Candida albicans' interactions with its human host

Tyc, Katarzyna Marta 25 February 2013 (has links)
Ansätze der mathematischen Modellierung ermöglichen die Analyse der dynamischen Eigenschaften biologischer Systeme und den Einfluß spezifischer Funktionen. Das Ziel dieser Arbeit ist es verschiedene Aspekte der Interaktionen zwischen Wirt und Krankheitserregern zu analysieren. In Kapitel 3 diskutiere ich ein Modell der zellulären Antwort auf Hitzeschockstress im Pilz Candida albicans. Das Modell in Form von gewöhnlichen Differentialgleichungen erörtert mehrere Aspekte des Systems, wie z.B. die erworbene Thermotoleranz und eine perfekte Anpassung an die Beanspruchung durch die Temperaturwechsel. Im Rahmen der Interaktionen zwischen Wirt und Krankheitserreger ist die Studie relevant, da die Entwicklung von Fieber eine primäre Antwort des Organismus auf eine Pilzinvasion ist. Die Dynamik von C. albicans Virulenzfaktoren, wie z.B. der Übergang vom Hefe- zum Hyphenstadium, und die Abwehrmechanismen des Wirts bestimmen den Zustand des Pilzes, d.h. ob er als Kommensale oder Krankheitserreger vorkommt. Mit Hilfe einer agenten-basierten Modellierungstechnik, in Kapitel 4, untersuche ich die Auswirkungen potenzieller medikamentöser Behandlungen von Pilzpopulationen und ihre Effektivität. In Kapitel 5 analysiere ich die Dynamik der C. albicans Hefe- und Hyphenpopulationen unter der Annahme, das zwischen den Individuen beider Populationen paarweise Wechselwirkungen bestehen, die zusätzlich von Fresszellen und Ernährungsbedingungen beeinflusst werden. Das erste Modell basiert auf den Prinzipien der Spieltheorie. Aus dieser Studie lässt sich die Hypothese aufstellen, dass sich im Verlauf der Infektion die evolutionäre Spieldynamik von der Snowdrift Spieldynamik in Richtung Gefangendilemma verschiebt. Im zweiten Modell untersuche ich die Umschaltraten zwischen Hefen und Hyphen. Das Modell zeigt, dass in Pilzpopulationen die Ausprägung verschiedener Phänotypen der Grund für die erhöhte Überlebensfähigkeit der Population sein könnte. / Mathematical modeling approaches facilitate the analysis of dynamic properties of mechanisms triggering specific functions of biological systems. Through this work I aim to shed light on various aspects of host-pathogen interactions. In Chapter 3, I discuss a model of heat shock stress response activated in the fungus Candida albicans. The model in form of ordinary differential equations reveals several features of the system, such as acquired thermotolerance and a perfect molecular adaptation to the thermal insult. The study is relevant in the context of host-pathogen interactions since development of fever is a primary host response to fungal invasion. The dynamics of C. albicans virulence factors, e.g., yeast to hypha transition, and defense mechanisms of the host determine the state of the fungi, i.e. whether to act as a commensal or as a foe. Through application of an agent-based modeling technique, in Chapter 4, I investigate effects of potential drug treatments on fungal populations and their effectivity in the fungal clearance. In Chapter 5, I analyze the dynamics of candida yeast and hyphal populations assuming pairwise interactions influenced by phagocytic cells and nutritional conditions. The first model is based on game theory principles. From the study it can be hypothesized that during the course of infection the evolutionary game dynamics shift from Snowdrift game dynamics toward Prisoners’ dilemma. In the second model, I examine switching rates between yeast and hypha. The model reveals that phenotypic variations may occur in order to increase the fitness of the population.
109

POLICY PROPOSAL ON THE FINANCE AND GROWTH RELATIONSHIP: UNDERSTANDING THE SWITCH FROM "VIRTUOUS" TO "BAD" CYCLES

LAURETTA, ELIANA 22 May 2014 (has links)
Studi condotti sulla crisi finanziaria del 2007-09 e la recessione economica hanno evidenziato l’inadeguatezza delle teorie predominanti e la loro inefficacia nel proporre adeguate soluzioni di policy. La presenza di moneta bancaria nell’economia e di un sistema finanziario caratterizzato da innovazione finanziaria e speculazione modificano profondamente la natura stessa del processo di credit creation. Una nuova prospettiva sulla relazione tra finanza e crescita economica necessita essere sviluppata cercando di colmare le lacune esistenti tra New Growth Theory e Evolutionary Theory, come J.A. Schumpeter (1934) e altri studiosi hanno evidenziato. I fattori strutturali sono alla base della persistente instabilita` finanziaria nell’economia. Questo studio tenta di spiegare l’ipotesi che sta alla base dell’intera analisi circa il passaggio avutosi nell'impianto strutturale dell'economia da un virtuous cycle ad un bad cycle, e dimostrare l’esistenza di cio` che definiamo wealth trap, la quale e` ipotizzata essere conseguenza di un sistema finanziario tecnologicamente avanzato, ma non socialmente avanzato. Un modello non lineare ad Agenti (AMB) chiamato BFSE (Based-line Financial System Economy) mostra , tramite la sperimentazione sul modello ICEACE(Erlingsson et al., 2011), evidenze sulla centralita` del sistema finanziario e dell’esistenza del bad cycle. Una discussione sulle macroprudential policies e le politiche strutturali e` introdotta. / Studies of the 2007-09 credit crisis and the resulting recession have revealed the inadequacy of the predominant theoretical frameworks and their failure to propose adequate policy solutions. The presence in the economy of bank money and a financial system characterized by financial innovation and speculation changes the nature of credit creation. As J.A. Schumpeter (1934) and others scholars have recognized, a new perspective on the financial-growth relationship needs to be developed by filling the gaps in New Growth Theory and Evolutionary Theory - two Sons of Schumpeter - and in some way combining them. Structural factors are at the bottom of the persistence of the financial instability in the economy. The goal of this research is to explain the main hypothesis of the historical passage of the economy from a virtuous to a bad cycle and to show the existence of the wealth trap, which is a consequence of a high-technologically advanced financial system within the economic system. A non-linear ABM (Agent Based Model) called BFSE provides, through experimentation using ICEACE model (Erlingsson et al., 2011), interesting evidences of the centrality of the financial system and the bad cycle. Macroprudential and structural policies are introduced.
110

Multiscale modeling and event tracking wireless technologies to improve efficiency and safety of the surgical flow in an OR suite / Modélisation multi-échelle assistée d’un système de détection d’événements : optimisation du fonctionnement et de la sécurité au sein des blocs opératoires

Joerger, Guillaume 16 June 2017 (has links)
Améliorer la gestion et l’organisation des blocs opératoires est une tâche critique dans les hôpitaux modernes, principalement à cause de la diversité et l’urgence des activités impliquées. Contrairement à l’aviation civile, qui a su optimiser organisation et sécurité, le management de bloc opératoire est plus délicat. Le travail ici présenté abouti au développement et à l’installation de nouvelles technologies assistées par ordinateur résolvant les problèmes quotidiens des blocs opératoires. La plupart des systèmes existants modélisent le flux chirurgical et sont utilisés seulement pour planifier. Ils sont basés sur des procédés stochastiques, n’ayant pas accès à des données sûres. Nous proposons une structure utilisant un modèle multi-agent qui comprend tous les éléments indispensables à une gestion efficace et au maintien de la sécurité dans les blocs opératoires, allant des compétences communicationnelles du staff, au temps nécessaire à la mise en place du service de nettoyage. Nous pensons que la multiplicité des ressources humaines engagées dans cette structure cause des difficultés dans les blocs opératoires et doit être prise en compte dans le modèle. En parallèle, nous avons construit un modèle mathématique de flux d’air entre les blocs opératoires pour suivre et simuler la qualité de l’environnement de travail. Trois points sont nécessaires pour la construction et le bon fonctionnement d’un ensemble de bloc opératoire : 1) avoir accès au statut du système en temps réel grâce au placement de capteurs 2) la construction de modèles multi-échelles qui lient tous les éléments impliqués et leurs infrastructures 3) une analyse minutieuse de la population de patients, du comportement des employés et des conditions environnementales. Nous avons développé un système robuste et invisible qui permet le suivi et la détection automatique d’événements dans les blocs. Avec ce système nous pouvons suivre l’activité à la porte d’entrée des blocs, puis l’avancement en temps réel de la chirurgie et enfin l’état général du bloc. Un modèle de simulation numérique de mécanique des fluides de plusieurs blocs opératoires est utilisé pour suivre la dispersion de fumée chirurgicale toxique, ainsi qu’un modèle multi-domaine qui évalue les risques de propagation de maladie nosocomiale entre les blocs. La combinaison de ces trois aspects amène une nouvelle dimension de sensibilisation à l’environnent des blocs opératoires et donne au staff un système cyber-physique capable de prédire des événements rares impactant la qualité, l’efficacité, la rentabilité et la sécurité dans l’hôpital. / Improving operating room management is a constant issue for modern large hospital systems who have to deal with the reality of day to day clinical activity. As opposed to other industrial sectors such as air civil aviation that have mastered the topic of industry organization and safety, progress in surgical flow management has been slower. The goal of the work presented here is to develop and implement technologies that leverage the principles of computational science to the application of OR suite problems. Most of the currently available models of surgical flow are used for planning purposes and are essentially stochastic processes due to uncertainties in the available data. We propose an agent-based model framework that can incorporate all the elements, from communication skills of the staff to the time it takes for the janitorial team to go clean an OR. We believe that human factor is at the center of the difficulty of OR suite management and should be incorporated in the model. In parallel, we use a numerical model of airflow at the OR suite level to monitor and simulate environment conditions inside the OR. We hypothesize that the following three key ingredients will provide the level of accuracy needed to improve OR management : 1) Real time updates of the model with ad hoc sensors of tasks/stages 2) Construction of a multi-scale model that links all key elements of the complex surgical infrastructure 3) Careful analysis of patient population factors, staff behavior, and environment conditions. We have developed a robust and non-obtrusive automatic event tracking system to make our model realistic to clinical conditions. Not only we track traffic through the door and the air quality inside the OR, we can also detect standard events in the surgical process. We propose a computational fluid dynamics model of a part of an OR suite to track dispersion of toxic surgical smoke and build in parallel a multidomain model of potential nosocomial contaminant particles flow in an OR suite. Combining the three models will raise the awareness of the OR suite by bringing to the surgical staff a cyber-physical system capable of prediction of rare events in the workflow and the safety conditions.

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