19,858 research outputs found

    An Analysis Tool for Push-Sum Based Distributed Optimization

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    The push-sum algorithm is probably the most important distributed averaging approach over directed graphs, which has been applied to various problems including distributed optimization. This paper establishes the explicit absolute probability sequence for the push-sum algorithm, and based on which, constructs quadratic Lyapunov functions for push-sum based distributed optimization algorithms. As illustrative examples, the proposed novel analysis tool can improve the convergence rates of the subgradient-push and stochastic gradient-push, two important algorithms for distributed convex optimization over unbalanced directed graphs. Specifically, the paper proves that the subgradient-push algorithm converges at a rate of O(1/t)O(1/\sqrt{t}) for general convex functions and stochastic gradient-push algorithm converges at a rate of O(1/t)O(1/t) for strongly convex functions, over time-varying unbalanced directed graphs. Both rates are respectively the same as the state-of-the-art rates of their single-agent counterparts and thus optimal, which closes the theoretical gap between the centralized and push-sum based (sub)gradient methods. The paper further proposes a heterogeneous push-sum based subgradient algorithm in which each agent can arbitrarily switch between subgradient-push and push-subgradient. The heterogeneous algorithm thus subsumes both subgradient-push and push-subgradient as special cases, and still converges to an optimal point at an optimal rate. The proposed tool can also be extended to analyze distributed weighted averaging.Comment: arXiv admin note: substantial text overlap with arXiv:2203.16623, arXiv:2303.1706

    Quantum Mechanics Lecture Notes. Selected Chapters

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    These are extended lecture notes of the quantum mechanics course which I am teaching in the Weizmann Institute of Science graduate physics program. They cover the topics listed below. The first four chapter are posted here. Their content is detailed on the next page. The other chapters are planned to be added in the coming months. 1. Motion in External Electromagnetic Field. Gauge Fields in Quantum Mechanics. 2. Quantum Mechanics of Electromagnetic Field 3. Photon-Matter Interactions 4. Quantization of the Schr\"odinger Field (The Second Quantization) 5. Open Systems. Density Matrix 6. Adiabatic Theory. The Berry Phase. The Born-Oppenheimer Approximation 7. Mean Field Approaches for Many Body Systems -- Fermions and Boson

    Bayesian networks for disease diagnosis: What are they, who has used them and how?

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    A Bayesian network (BN) is a probabilistic graph based on Bayes' theorem, used to show dependencies or cause-and-effect relationships between variables. They are widely applied in diagnostic processes since they allow the incorporation of medical knowledge to the model while expressing uncertainty in terms of probability. This systematic review presents the state of the art in the applications of BNs in medicine in general and in the diagnosis and prognosis of diseases in particular. Indexed articles from the last 40 years were included. The studies generally used the typical measures of diagnostic and prognostic accuracy: sensitivity, specificity, accuracy, precision, and the area under the ROC curve. Overall, we found that disease diagnosis and prognosis based on BNs can be successfully used to model complex medical problems that require reasoning under conditions of uncertainty.Comment: 22 pages, 5 figures, 1 table, Student PhD first pape

    Strategies for Early Learners

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    Welcome to learning about how to effectively plan curriculum for young children. This textbook will address: • Developing curriculum through the planning cycle • Theories that inform what we know about how children learn and the best ways for teachers to support learning • The three components of developmentally appropriate practice • Importance and value of play and intentional teaching • Different models of curriculum • Process of lesson planning (documenting planned experiences for children) • Physical, temporal, and social environments that set the stage for children’s learning • Appropriate guidance techniques to support children’s behaviors as the self-regulation abilities mature. • Planning for preschool-aged children in specific domains including o Physical development o Language and literacy o Math o Science o Creative (the visual and performing arts) o Diversity (social science and history) o Health and safety • Making children’s learning visible through documentation and assessmenthttps://scholar.utc.edu/open-textbooks/1001/thumbnail.jp

    Variables controlling the resurgence of previously reinforced behaviour in hens

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    Resurgence is defined as the occurrence of previously reinforced behaviours when reinforcer delivery ceases for a recently reinforced behaviour. In five experiments, variables suggested to control the degree of occurrence of a first-trained behaviour during the extinction of a second-trained behaviour (resurgence) were investigated. All experiments used hens and behaviours were selected from door push, key peck, and head bob. In Experiment 1, using 6 naive hens, Behaviour 1 was reinforced on a random-interval (RI) 60-s schedule followed by two sessions of extinction. Each occurrence of Behaviour 2 was then reinforced followed by another period of extinction. The degree of occurrence of Behaviour 1 during the final extinction was less than that which occurred during the period of Behaviour 1 extinction, suggesting that the extinction of Behaviour 2 did not increase the occurrence of Behaviour 1. This result failed to support the idea that resurgence is induced by the extinction of Behaviour 2. In Experiment 2, using the same hens and an additional hen, Experiment 1 was repeated five times and then there were either 0 or 9 sessions of Behaviour 1 extinction in a further five conditions. The degree of resurgence was generally less when there were 9 sessions than when there were no sessions but not consistently different from either when there were 2 sessions. Experiment 3 used six naive hens. Two first-trained behaviours were initially reinforced on RI 45-s schedules under a multiple schedule. One first behaviour then received a period of extinction and then each occurrence of two second behaviours was reinforced under the multiple schedule followed by extinction. The sequence from training of the first behaviours to the extinction of the second behaviours was repeated 10 times with the number of occurrences of the component for which extinction was in effect for the first behaviour varying across conditions from 12 to 0. The degree of resurgence was an inverse function of the amount of Behaviour 1 extinction. Experiment 4 used six naive hens. In a multiple schedule two first behaviours were reinforced on RI 20-s schedules and then two second behaviours were reinforced followed by extinction. This was repeated 8 times with the RI schedule in effect for one of the second behaviours varying from 80 s to 10 s across conditions while the other remained at 40 s. The degree of occurrence of Behaviour 1 when Behaviour 2 was reinforced was a direct function of the varied RI schedule of Behaviour 2. The degree of resurgence of Behaviour 1 in extinction was an inverse function of the varied RI schedule of Behaviour 2. The degree of resurgence was also inversely related to the degree of occurrence of this Behaviour 1 when Behaviour 2 was reinforced. Experiment 5 used five naive hens and one hen from Experiment 3 in a multiple-schedule design where the length of training of the second behaviours varied from 124 to O occurrences of a component over three conditions. No effect of this was found on the degree of resurgence. The results are consistent with the hypothesis that resurgence is the result of the prevention of extinction of Behaviour 1 by the reinforcement of Behaviour 2, but they are not definitive proof that this hypothesis is correct. Models derived from the Generalised Matching Law and Behavioural Momentum are also proposed as descriptions of resurgence

    Gamification in E-Learning: game factors to strengthen specific English pronunciation features in undergraduate students at UPTC Sogamoso

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    Appendix A Characterization survey (104), Appendix B. EFL Students’ questionnaire (109), Appendix C. Characterization survey: data treatment question (113), Appendix D. Informed consent letter, English version (114), Appendix E. Carta de consentimiento informado, versión en español (117), Appendix F. Time Schedule (120), Appendix G. Sample Challenges at Moodle (126), Appendix H. Participants’ questionnaire results (128).La gamificación es un término que suele denotar el uso de componentes del juego en situaciones no relacionadas con el juego en sí para crear experiencias de aprendizaje agradables, divertidas y motivadoras para los estudiantes (Werbach y Hunter, 2012). Por lo tanto, el análisis de los factores básicos de los juegos se convierte en algo esencial a la hora de definir y utilizar la gamificación como estrategia de mediación del inglés como lengua extranjera para fortalecer rasgos específicos de pronunciación en los estudiantes de pregrado de la UPTC Sogamoso. El procedimiento de estudio se basa en la investigación acción mediante la implementación de la estrategia de gamificación para la mediación en la pronunciación del inglés, orientada a treinta estudiantes de diferentes programas de ingeniería, administración y tecnología con niveles heterogéneos de dominio del inglés. Las actividades se centran principalmente en la producción de sonidos, el ritmo, el acento y la entonación, los rasgos de pronunciación segmental y suprasegmental. Los resultados arrojaron una evidente mejora en las características segméntales y suprasegmentales de la percepción en la pronunciación de los participantes así como la contribución del objetivo de los juegos a la instrucción fonética y fonológica, la sensación en el juego a la motivación para mejorar la pronunciación, el reto establecido en los juegos a la actitud positiva de los participantes, y la sociabilidad a la exposición practica de la pronunciación inglesa.Gamification is a relatively new term that often denotes the use of game components in situations unrelated to the game itself to create enjoyable, fun, and motivating learning experiences for students (Werbach and Hunter, 2012). Therefore, analyzing the games' basic factors becomes essential when defining and using gamification as a strategy for English as Foreign Language mediation to strengthen specific pronunciation features in UPTC Sogamoso undergraduate students. The study procedure is based on action research by implementing the gamification strategy for mediation in English pronunciation, oriented to thirty students from different engineering, management, and technology programs at heterogeneous levels of English proficiency. The activities mainly focus on sound production, rhythm, stress, and intonation, segmental and suprasegmental pronunciation features. The results showed an evident improvement in the segmental and suprasegmental features of the participants' pronunciation perception as well as the contribution of game goals to phonetics and phonological instruction, the game sensation to the motivation for pronunciation improvement, the game challenge to the participants' positive attitude, and the sociality to the English pronunciation exposure practice

    Exploring the Structure of Scattering Amplitudes in Quantum Field Theory: Scattering Equations, On-Shell Diagrams and Ambitwistor String Models in Gauge Theory and Gravity

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    In this thesis I analyse the structure of scattering amplitudes in super-symmetric gauge and gravitational theories in four dimensional spacetime, starting with a detailed review of background material accessible to a non-expert. I then analyse the 4D scattering equations, developing the theory of how they can be used to express scattering amplitudes at tree level. I go on to explain how the equations can be solved numerically using a Monte Carlo algorithm, and introduce my Mathematica package treeamps4dJAF which performs these calculations. Next I analyse the relation between the 4D scattering equations and on-shell diagrams in N = 4 super Yang-Mills, which provides a new perspective on the tree level amplitudes of the theory. I apply a similar analysis to N = 8 supergravity, developing the theory of on-shell diagrams to derive new Grassmannian integral formulae for the amplitudes of the theory. In both theories I derive a new worldsheet expression for the 4 point one loop amplitude supported on 4D scattering equations. Finally I use 4D ambitwistor string theory to analyse scattering amplitudes in N = 4 conformal supergravity, deriving new worldsheet formulae for both plane wave and non-plane wave amplitudes supported on 4D scattering equations. I introduce a new prescription to calculate the derivatives of on-shell variables with respect to momenta, and I use this to show that certain non-plane wave amplitudes can be calculated as momentum derivatives of amplitudes with plane wave states
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