376 research outputs found
Bayesian Semi- and Non-parametric Analysis for Spatially Correlated Survival Data
Flexible incorporation of both geographical patterning and risk effects in cancer survival models is becoming increasingly important, due in part to the recent availability of large cancer registries. The analysis of spatial survival data is challenged by the presence of spatial dependence and censoring for survival times. Accurately modeling the risk factors and geographical pattern that explain the differences in survival is particularly of interest. Within this dissertation, the first chapter reviews commonlyused baseline priors, semiparametric and nonparametric Bayesian survival models and recent approaches for accommodating spatial dependence, both conditional and marginal. The last three chapters contribute three flexible survival models: (1) a proportional hazards model with areal-level covariate-adjusted frailties with application to county-level breast cancer survival data, (2) a marginal Bayesian nonparametric model for time to disease arrival of threatened amphibian populations, and (3) a generalized accelerated failure time model with spatial intrinsic conditionally autoregressive frailties with application to county-level prostate cancer data. An R package spBayesSurv is developed to examine all the proposed models along with some traditional spatial survival models
An Empirical Study on Chinese EFL Learners’ Critical Reading Strategies
Critical reading is of great importance in foreign language learning. This paper reports an empirical study on Chinese EFL learners’ critical reading strategies. The subjects were 120 senior high school English learners, and the instruments included a questionnaire and a reading test paper. Detailed analysis of the quantitative data by SPSS22.0 has yielded the findings as follows: (1) Most learners were in urgent need of training on the proper choice and use of critical reading strategies. (2) Significant differences were found to exist between high-score and low-score group regarding structure analysis, rhetoric analysis and holistic evaluation. (3) Both high score and low score learners were found be less skilled in using the strategy of background analysis. It is suggested that the positive critical reading strategies should be encouraged and fostered in English language teaching and learning
Epidemic Discourse and National Image Construction From the Perspective of Visual Grammar Theory
A good national image helps to enhance the country’s voice in international diplomatic activities, and helps to strengthen the country’s soft power. As an important part of social reality, discourse plays an important role in the process of international diplomatic scene and national image construction. In recent years, with the global spread of the COVID-19 epidemic, news and public opinion around the world have focused on it, and a large number of news reports have emerged. Based on the theoretical framework of visual grammar theory and Halliday’s systemic functional linguistics theory, this study analyzes the relationship between epidemic discourse and national image structure from three aspects: reproduction function, interaction function and composition function, and puts forward targeted suggestions for building a good national image
Tars: Timeliness-aware Adaptive Replica Selection for Key-Value Stores
In current large-scale distributed key-value stores, a single end-user
request may lead to key-value access across tens or hundreds of servers. The
tail latency of these key-value accesses is crucial to the user experience and
greatly impacts the revenue. To cut the tail latency, it is crucial for clients
to choose the fastest replica server as much as possible for the service of
each key-value access. Aware of the challenges on the time varying performance
across servers and the herd behaviors, an adaptive replica selection scheme C3
is proposed recently. In C3, feedback from individual servers is brought into
replica ranking to reflect the time-varying performance of servers, and the
distributed rate control and backpressure mechanism is invented. Despite of
C3's good performance, we reveal the timeliness issue of C3, which has large
impacts on both the replica ranking and the rate control, and propose the Tars
(timeliness-aware adaptive replica selection) scheme. Following the same
framework as C3, Tars improves the replica ranking by taking the timeliness of
the feedback information into consideration, as well as revises the rate
control of C3. Simulation results confirm that Tars outperforms C3.Comment: 10pages,submitted to ICDCS 201
A Review of Teacher Transformational Leadership in Higher Education: The Fourth Wave of Teacher Leadership
Transformational leadership offers world-wide scholars a new paradigm to leadership research, and it occupies a central place in leadership research and is rendered as a crucial indicator of promoting students’ academic outcomes. This literature review sought to provide a general picture of transformational leadership as well as its application in higher education context, through which its readers can have a better understanding of what has been done about the topic and what remains to be done in the future. It can seen that the examination of the existing literature further confirmed the validity and effectiveness of teacher transformational leadership in higher educational settings
spBayesSurv: Fitting Bayesian Spatial Survival Models Using R
Spatial survival analysis has received a great deal of attention over the last 20 years due to the important role that geographical information can play in predicting survival. This paper provides an introduction to a set of programs for implementing some Bayesian spatial survival models in R using the package spBayesSurv. The function survregbayes includes the three most commonly-used semiparametric models: proportional hazards, proportional odds, and accelerated failure time. All manner of censored survival times are simultaneously accommodated including uncensored, interval censored, current-status, left and right censored, and mixtures of these. Left-truncated data are also accommodated. Time-dependent covariates are allowed under the piecewise constant assumption. Both georeferenced and areally observed spatial locations are handled via frailties. Model fit is assessed with conditional Cox-Snell residual plots, and model choice is carried out via the log pseudo marginal likelihood, the deviance information criterion and the WatanabeAkaike information criterion. The accelerated failure time frailty model with a covariatedependent baseline is included in the function frailtyGAFT. In addition, the package also provides two marginal survival models: proportional hazards and linear dependent Dirichlet process mixtures, where the spatial dependence is modeled via spatial copulas. Note that the package can also handle non-spatial data using non-spatial versions of the aforementioned models
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