1,965,387 research outputs found
Q-learning with censored data
We develop methodology for a multistage decision problem with flexible number
of stages in which the rewards are survival times that are subject to
censoring. We present a novel Q-learning algorithm that is adjusted for
censored data and allows a flexible number of stages. We provide finite sample
bounds on the generalization error of the policy learned by the algorithm, and
show that when the optimal Q-function belongs to the approximation space, the
expected survival time for policies obtained by the algorithm converges to that
of the optimal policy. We simulate a multistage clinical trial with flexible
number of stages and apply the proposed censored-Q-learning algorithm to find
individualized treatment regimens. The methodology presented in this paper has
implications in the design of personalized medicine trials in cancer and in
other life-threatening diseases.Comment: Published in at http://dx.doi.org/10.1214/12-AOS968 the Annals of
Statistics (http://www.imstat.org/aos/) by the Institute of Mathematical
Statistics (http://www.imstat.org
The role of structural characteristics in video-game play motivation: a Q-methodology study
Until recently, there has been very little naturalistic study of what gaming experiences are like, and how gaming fits into people’s lives. Using a recently developed structural characteristic taxonomy of video games, this study examined the psycho-structural elements of computer games that motivate gamers to play them. Using Q-Sort methodology, 40 gamers participated in an online Q-sort task. Results identified six distinct types of gamers based on the factors generated: (a) story-driven solo gamers; (b) social gamers; (c) solo limited gamers; (d) hardcore online gamers; (e) solo control=identity gamers; and (f ) casual gamers. These gaming types are discussed, and a brief evaluation of similar and unique elements of the different types of gamer is also offered. The current study shows Q-methodology to be a relevant and applicable method in the psychological research of gaming
A Q-methodology study of parental understandings of infant immunisation : implications for health-care advice.
This study used Q-methodology to explore systematically parental judgements about infant immunisation. A total of 45 parents completed a 31-statement Q-sort. Data were collected after vaccination in general practitioner practices or a private day nursery. Q factor analysis revealed four distinct viewpoints: a duty to immunise based on medical benefits, child-orientated protection based on parental belief, concern and distress and surprise at non-compliance. Additionally, there was a common view among parents that they did not regret immunising their children. Implications of these results are discussed in terms of health-care policy and future research
Optimized optomechanical crystal cavity with acoustic radiation shield
We present the design of an optomechanical crystal nanobeam cavity that
combines finite-element simulation with numerical optimization, and considers
the optomechanical coupling arising from both moving dielectric boundaries and
the photo-elastic effect. Applying this methodology results in a nanobeam with
an experimentally realized intrinsic optical Q-factor of 1.2x10^6, a mechanical
frequency of 5.1GHz, a mechanical Q-factor of 6.8x10^5 (at T=10K), and a
zero-point-motion optomechanical coupling rate of g=1.1MHz.Comment: 4 pages, 4 figure
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