320 research outputs found

    Exploration-Exploitation in Multi-Agent Learning: Catastrophe Theory Meets Game Theory

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    Exploration-exploitation is a powerful and practical tool in multi-agent learning (MAL), however, its effects are far from understood. To make progress in this direction, we study a smooth analogue of Q-learning. We start by showing that our learning model has strong theoretical justification as an optimal model for studying exploration-exploitation. Specifically, we prove that smooth Q-learning has bounded regret in arbitrary games for a cost model that explicitly captures the balance between game and exploration costs and that it always converges to the set of quantal-response equilibria (QRE), the standard solution concept for games under bounded rationality, in weighted potential games with heterogeneous learning agents. In our main task, we then turn to measure the effect of exploration in collective system performance. We characterize the geometry of the QRE surface in low-dimensional MAL systems and link our findings with catastrophe (bifurcation) theory. In particular, as the exploration hyperparameter evolves over-time, the system undergoes phase transitions where the number and stability of equilibria can change radically given an infinitesimal change to the exploration parameter. Based on this, we provide a formal theoretical treatment of how tuning the exploration parameter can provably lead to equilibrium selection with both positive as well as negative (and potentially unbounded) effects to system performance.Comment: Appears in the 35th AAAI Conference on Artificial Intelligenc

    Celebration 2017 Abstract Booklet and Student Presentation Schedule

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    "Flat Tax": caracterização da investigação

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    O aumento de interesse pelo tema “Flat Tax” a nível político em diversos países, suscitado pelos resultados obtidos nos países que adotaram um regime proporcional de tributação sobre os rendimentos pessoais, motivou o desenvolvimento desta dissertação, com o objetivo de caracterizar a investigação sobre a “Flat Tax” no contexto da fiscalidade. Para tal, realizou-se uma análise a uma amostra de 109 artigos científicos recolhidos da plataforma Scopus, à luz de indicadores bibliométricos, e desenvolveu-se uma tabela resumo com as conclusões dos principais artigos da amostra, seguindo uma metodologia PRISMA. A análise aos artigos permitiu concluir que o interesse académico pelo tema tem vindo a aumentar ao longo das décadas, já que tanto o número de artigos publicados como o número de citações aos artigos analisados tiveram um crescimento positivo. Adicionalmente, foi possível concluir que o tema é maioritariamente estudado por autores vinculados a países europeus, ainda que o país em que o tema mais suscitou interesse nos autores tenha sido nos EUA, e que os artigos são desenvolvidos maioritariamente em coautoria. Foi também possível concluir que o tema desperta interesse em diversas áreas de estudo e que, consequentemente, os artigos são publicados em múltiplas revistas científicas. Importa ainda salientar que as principais keywords associadas ao tema são “tax reform” e “tax system”. Finalmente, interessa referir que devido à multitude de áreas relacionadas com a flat tax abordadas nos artigos em causa, as conclusões obtidas nos mesmos são bastante diferentes, e por vezes divergentes.The increased interest in the “Flat Tax” topic at a political level in several countries, motivated by the results obtained in countries that have adopted a proportional taxation system on personal income, prompted the development of this dissertation, with the objective of characterising the investigation on “Flat Tax” in the context of taxation. To this end, a sample of 109 scientific articles collected from the Scopus platform was analysed, in light of bibliometric indicators, and a summary table was developed with the conclusions of the main articles of the sample, following a PRISMA methodology. The analysis of the articles allowed to conclude that the academic interest in the subject has been increasing over the last decades, since both the number of articles published and the number of citations to the articles analysed had a positive growth. In addition, it was concluded that the subject is mostly studied by authors linked to European countries, although the country in which the subject generated most interest was the USA, and that the articles are mostly coauthored. It was also possible to conclude that the subject raises interest in various areas of study and that, consequently, articles are published in multiple scientific journals. It should also be noted that the main keywords associated with the topic are "tax reform" and "tax system". Finally, it is worth mentioning that due to the multitude of areas related to the flat tax addressed in the articles in question, the conclusions obtained in them are quite different, and sometimes divergent

    2013 Oklahoma Research Day Full Program

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    This document contains all abstracts from the 2013 Oklahoma Research Day held at the University of Central Oklahoma

    Modeling complex cell regulation in the zebrafish circadian clock

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    The interdisciplinary "systems biology" approach of combining traditional biological investigations with tools from the mathematical and computer sciences has enabled novel insights into many highly complex and dynamic biological systems. The use of models has, for instance, revealed much about the intricate feedback mechanisms and acute importance of gene regulatory networks, and one such network of special note is our internal time keeper, or circadian clock. The circadian clock plays a pivotal role in modulating critical physiological processes, and has also been implicated, either directly or indirectly, in a whole range of pathological states. This research project investigates how the underlying dynamics of the circadian clock in the zebrafish model organism may be captured by a mathematical model, considering in particular the entrainment effect due to external cues such as light. Simulated data is contrasted with experimental results from different light regime experiments to validate the model and guide its refinement. Furthermore, various statistical methods are implemented to process the raw data and support its analysis. Extending the initial deterministic approach to take into account stochastic effects and additive population level effects emerges as a powerful means of representing the circadian signal decay in prolonged darkness, as well as light initiated re-synchronization as a strong component of entrainment. Consequently, it emerges that stochastic effects may be considered an essential feature of the circadian clock in zebrafish. A further cornerstone of the project is the implementation of an integrated simulation environment, including a Sequential Monte Carlo parameter estimation function, which succeeds in predicting a range of previously determined and also novel suitable parameter values. However, considerable difficulties in obtaining parameter values that satisfy the entire range of important target values simultaneously highlights the inherent complexity of accurately simulating the circadian clock

    Cells in Space

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    Discussions and presentations addressed three aspects of cell research in space: the suitability of the cell as a subject in microgravity experiments, the requirements for generic flight hardware to support cell research, and the potential for collaboration between academia, industry, and government to develop these studies in space. Synopses are given for the presentations and follow-on discussions at the conference and papers are presented from which the presentations were based. An Executive Summary outlines the recommendations and conclusions generated at the conference

    An Anatomy Based Health Education Curriculum Taught by Medical Students May Improve High School Students Health Knowledge

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    To date, few high school based interventions have been shown to have lasting effects on adolescents\u27 health behaviors. The need for health interventions targeting adolescents is underscored by data showing that several health behaviors with significant short and long term adverse effects begin in early adolescence and become progressively more prevalent toward late adolescence. This project tested the efficacy of a novel anatomy based health education curriculum at increasing health knowledge. The course was taught by first year Yale medical students. The curriculum placed emphasis on nutrition, physical activity and infectious disease. Forty Juniors from Career High School visited Yale\u27s anatomy lab once every two weeks for ten hour-long sessions. In addition to visits to the anatomy lab, students completed two class projects, one covered nutrition and the other focused on exercise. Four additional sessions at Career High School were dedicated to the class projects. Pre and post test analysis showed an improvement in health knowledge with a thirteen percentage point improvement on a standardized health knowledge survey. The students\u27 performance was compared to a control cohort of thirty-one students who were not exposed to the curriculum. Students exposed to the curriculum had a nineteen percentage point advantage compared to control students who had not been exposed. Curriculum efficacy as demonstrated by this small cohort validate further testing with larger cohorts and more vigorous controls as well as separate testing to measure changes in health behavior attributable to curriculum exposure

    Design and elaboration of novel drug eluting stents to produce tailored releases aiming for the reduction of restenosis after implantation

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    Les malalties d'artèria coronària són el tipus més comú de malaltia cardíaca, matant a més de 385,000 persones anualment. Fins a la data, s'han provat moltes estratègies diferents a l'hora de plantejar tractaments que mantinguin les respostes inflamatòries al mínim. Entre aquests, l'ús de nanopartícules, recobriments multicapa i teràpia gènica destaquen com algunes de les estratègies terapèutiques noves més prometedores. L'ús de stents cardíacs s'ha mantingut al llarg dels anys amb diferents dissenys i recobriments, aconseguint millors resultats amb cada nova generació. Encara que el seu ús està justificat, els seus resultats no són òptims, creant la necessitat de desenvolupar millors estratègies per tractar aquest tipus de malalties. Entenem que un control total de l'alliberament de la càrrega farmacològica d'un dispositiu mèdic pot canviar profundament els resultats d'un pacient, convertint-se així en una prioritat del nostre treball. Presentem una forma de produir recobriments, a escala industrial i de laboratori, orientats per a dispositius mèdics i que s'utilitzen per produir recobriments multicapa a mida per stents amb alliberament de fàrmac. A més d'això, també es presenta un enfocament per tractar malalties d'artèria coronària a través de la teràpia gènica amb nanoportadors, el que obre noves possibilitats per a tractaments localitzats emprant stents amb alliberament de fàrmac. Començant amb l'elaboració de metodologies i instruments necessaris per a produir recobriments a mida, es creen i estudien nous dissenys de stent al llarg d'aquest treball. Això permet la producció de nous recobriments i sistemes d’alliberació els quals són provats in-vitro i in-vivo per demostrar la seva efectivitat. En conclusió, aquesta tesi demostra que es pot aconseguir un alliberament de fàrmacs a mida mitjançant dissenys multicapa i alliberament amb nanoportadors, aplicable a stents amb alliberament de fàrmac per obtenir una reducció en les taxes de reestenosi amb resultats prometedors.Las enfermedades de arteria coronaria son el tipo más común de enfermedad cardíaca, matando a más de 385,000 personas anualmente. Hasta la fecha, se han probado muchos enfoques distintos a la hora de plantear tratamientos que mantengan las respuestas inflamatorias al mínimo. Entre estos, el uso de nanoparticulas, recubrimientos multicapa y terapia génica destacan como algunas de las estrategias terapéuticas novedosas más prometedoras. El uso de stents cardíacos se ha mantenido a lo largo de los años con diferentes diseños y recubrimientos, logrando mejores resultados con cada nueva generación. Aunque su uso está justificado, sus resultados no son óptimos, creando la necesidad de desarrollar mejores estrategias para tratar este tipo de enfermedades. Entendemos que un control total de la liberación de la carga farmacológica de un dispositivo médico puede cambiar profundamente los resultados de un paciente, convirtiéndose así en una prioridad de nuestro trabajo. Presentamos una forma de producir recubrimientos, a escala industrial y de laboratorio, orientados para dispositivos médicos y que se utilizan para producir recubrimientos multicapa a medida para stents con liberación de fármaco. Además de esto, también se presenta un enfoque para tratar enfermedades de arteria coronaria a través de la terapia génica con nanoportadores, lo que abre nuevas posibilidades para tratamientos localizados empleando stents con liberación de fármaco. Comenzando con la elaboración de metodologías e instrumentos necesarios para producir recubrimientos a medida, se crean y estudian nuevos diseños de stent a lo largo de este trabajo. Esto permite la producción de nuevos recubrimientos y sistemas de liberación los cuales son probados in-vitro e in-vivo para demostrar su efectividad. En conclusión, esta tesis demuestra que se puede lograr una liberación de fármacos a medida mediante diseños multicapa y liberación con nanoportadores, aplicable a stents con liberación de fármaco para obtener una reducción en las tasas de reestenosis con resultados prometedores.Coronary artery disease is the most typical type of heart disease, killing more than 385,000 people annually. Up to date, many different approaches have been tested in order to treat patients while trying to keep inflammatory responses to a minimum. Among these, the use of nanocarriers, multilayered coatings and gene therapy stand out as some of the most promising novel therapeutic strategies tested lately. Stents have been used throughout the years with different designs and coatings, achieving enhanced healing results with every new generation. Although their use is justified their results are not optimal, creating a need to develop better strategies to treat coronary artery diseases. We understand that a total liberation control of the pharmacological drug load from a medical device can profoundly change a patient’s outcome, therefore, becoming a priority of our work. Here, we present a way of producing in-lab and industrial scaled coatings for medical devices which are used to produce tailored multilayered coatings for drug eluting stents. Apart from this, an approach to treat coronary artery disease through gene therapy with nanocarriers is also introduced, opening new possibilities for localized treatments with drug eluting stents. Starting with the elaboration of methodologies and instrumentation required to produce tailored coatings, novel stent designs are created and studied in this work. This enables the production of new coatings and delivery systems which are tested in-vitro and in-vivo in order to prove their effectiveness. In conclusion, this thesis demonstrated that a tailored drug release can be achieved through multilayered designs and nanoparticle liberations, which can be applied to drug eluting stents to obtain a reduction in restenosis rates with promising results
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