184 research outputs found
Parallel hierarchical sampling:a general-purpose class of multiple-chains MCMC algorithms
This paper introduces the Parallel Hierarchical Sampler (PHS), a class of Markov chain Monte Carlo algorithms using several interacting chains having the same target distribution but different mixing properties. Unlike any single-chain MCMC algorithm, upon reaching stationarity one of the PHS chains, which we call the âmotherâ chain, attains exact Monte Carlo sampling of the target distribution of interest. We empirically show that this translates in a dramatic improvement in the samplerâs performance with respect to single-chain MCMC algorithms. Convergence of the PHS joint transition kernel is proved and its relationships with single-chain samplers, Parallel Tempering (PT) and variable augmentation algorithms are discussed. We then provide two illustrative examples comparing the accuracy of PHS with
Concurrent bandits and cognitive radio networks
We consider the problem of multiple users targeting the arms of a single
multi-armed stochastic bandit. The motivation for this problem comes from
cognitive radio networks, where selfish users need to coexist without any side
communication between them, implicit cooperation or common control. Even the
number of users may be unknown and can vary as users join or leave the network.
We propose an algorithm that combines an -greedy learning rule with a
collision avoidance mechanism. We analyze its regret with respect to the
system-wide optimum and show that sub-linear regret can be obtained in this
setting. Experiments show dramatic improvement compared to other algorithms for
this setting
Aplicação da tecnologia PFCP integrada ao CAPP em ambiente de ferramentaria /
Dissertação (Mestrado) - Universidade Federal de Santa Catarina, Centro Tecnológico
Thompson Sampling with Virtual Helping Agents
We address the problem of online sequential decision making, i.e., balancing
the trade-off between exploiting the current knowledge to maximize immediate
performance and exploring the new information to gain long-term benefits using
the multi-armed bandit framework. Thompson sampling is one of the heuristics
for choosing actions that address this exploration-exploitation dilemma. We
first propose a general framework that helps heuristically tune the exploration
versus exploitation trade-off in Thompson sampling using multiple samples from
the posterior distribution. Utilizing this framework, we propose two algorithms
for the multi-armed bandit problem and provide theoretical bounds on the
cumulative regret. Next, we demonstrate the empirical improvement in the
cumulative regret performance of the proposed algorithm over Thompson Sampling.
We also show the effectiveness of the proposed algorithm on real-world
datasets. Contrary to the existing methods, our framework provides a mechanism
to vary the amount of exploration/ exploitation based on the task at hand.
Towards this end, we extend our framework for two additional problems, i.e.,
best arm identification and time-sensitive learning in bandits and compare our
algorithm with existing methods.Comment: 14 pages, 8 figure
State v. Hines Respondent\u27s Brief Dckt. 42983
https://digitalcommons.law.uidaho.edu/not_reported/3211/thumbnail.jp
Estudo do esfregaço vaginal de ratas submetidas a transplante autĂłlogo de ovĂĄrio: impacto do precondicionamento isquĂȘmico remoto
PURPOSE: To evaluate the remote ischemic preconditioning (R-IPC) impact on the quality of the ovarian graft by means of vaginal smear of transplanted rats. METHODS: Sixty rats were used divided in six groups: Control; Fresh transplant (TxF); Cryopreserved transplant (TxC); R-IPC; R-IPC + fresh transplant (TxF+R-IPC); R-IPC + cryopreserved transplant (TxC+R-IPC). R-IPC was performed in the common iliac artery. Autologous ovarian tissue was implanted integrally in the retro peritoneum. On the first PO day, vaginal smear collection was daily initiated. After 30 days, the PO day when the estrous cycle was re-initiated was considered for analysis as well as the estrous days and the number of estrous cycles. RESULTS: R-IPC showed a tendency to an early estrus re-initiation (p>0.05) as well as increase the number of cycles in the fresh transplanted group while in the cryopreserved transplant the number of cycles was similar, regardless of the stimulus R-IPC (p>0.05). The animals which had undergone fresh grafts had a longer estrous period than the ones which had undergone cryopreserved grafts, with or without R-IPC (p0,05), assim como aumento no nĂșmero de cilcos estrais nos grupos com transplante fresco enquanto que no criopreservado o nĂșmero de ciclos foi semelhante, independente do PCI-R (p>0,05). Os animais que receberam enxertos frescos apresentaram mais dias na fase estro do que os criopreservados, com ou sem PCI-R. CONCLUSĂO: O PCI-R promoveu retorno mais precoce da atividade ovariana no PO e maior freqĂŒĂȘncia de estro, sendo os resultados mais consistentes nos enxertos frescos do que nos criopreservados.Fundação de Amparo Ă Pesquisa do Estado de SĂŁo Paulo (FAPESP)UNIFESP Surgery and Research Postgraduate ProgramUniversidade Federal de SĂŁo Paulo (UNIFESP) Department of PathologyUNIFESP Gynecological DivisionUniversidade Federal de SĂŁo Paulo (UNIFESP) Department of Morphology Histology and Structural Biology DivisionUniversidade Federal de SĂŁo Paulo (UNIFESP) Department of Surgery Operative Technique and Experimental Surgery DivisionUNIFESP, Surgery and Research Postgraduate ProgramUNIFESP, Department of PathologyUNIFESP, Gynecological DivisionUNIFESP, Department of Morphology Histology and Structural Biology DivisionUNIFESP, Department of Surgery Operative Technique and Experimental Surgery DivisionSciEL
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