Modified check loss for efficient estimation via model selection in quantile regression

The check loss function is used to define quantile regression. In cross-validation, it is also employed as a validation function when the true distribution is unknown. However, our empirical study indicates that validation with the check loss often leads to overfitting the data. In this work, we suggest a modified or L2-adjusted check loss which rounds the sharp corner in the middle of check loss. This has the effect of guarding against overfitting to some extent. The adjustment is devised to shrink to zero as sample size grows. Through various simulation settings of linear and nonlinear regressions, the improvement due to modification of the check loss by quadratic adjustment is examined empirically.     

Threshold Estimation via Group Orthogonal Greedy Algorithm

A threshold autoregressive (TAR) model is an important class of nonlinear time series models that possess many desirable features such as asymmetric limit cycles and amplitude-dependent frequencies. Statistical inference for the TAR model encounters a major difficulty in the estimation of thresholds, however. This article develops an efficient procedure to estimate the thresholds. The procedure first transforms multiple-threshold detection to a regression variable selection problem, and then employs a group orthogonal greedy algorithm to obtain the threshold estimates. Desirable theoretical results are derived to lend support to the proposed methodology. Simulation experiments are conducted to illustrate the empirical performances of the method. Applications to U.S. GNP data are investigated.     

示范性软件学院人才培养的实训教学探索与实践——以肇庆学院软件学院为例

分析了高校IT专业人才培养与IT企业需求之间的差距及原因，提出校企合作这一省级示范性软件学院实训的重要环节，并结合肇庆学院软件学院的实际情况给出了实训的内涵、思路和模式。     

物流均衡理论构建及应用研究

随着经济水平的不断提高,物流在调整经济结构,促进经济增长等方面发挥着越来越大的作用。物流业进入以转型升级为主线的发展新阶段,现有理论无法有效支撑物流的发展。通过对均衡理论的研究,结合物流系统的特点,提出了物流均衡理论,给出了数量均衡、结构均衡、时间均衡的三维均衡结构,分析物流均衡的发展过程以及影响物流均衡层次的关键因素,对物流均衡的应用进行探讨,以期丰富物流相关理论。     

一种基于MapReduce的贝叶斯海量文本并行分类算法

面对海量数据带来的冲击,传统的单机版贝叶斯分类程序存在处理的数据集有限、内存瓶颈和耗时较长等问题.本文通过对朴素贝叶斯模型进行研究,设计并实现了一种基于Map Reduce的朴素贝叶斯文本分类算法.实验表明,该算法具有较好的扩展性和加速比,可适用于海量密集文本分类.     

Optimistic but Confused: Perceptions about the Mission and Core Values of Social Work in Vietnam by Vietnamese Policy‐makers,Social Work Faculty and Practitioners

In 2010, the Vietnamese government officially recognized social work as a profession. This study explores whether key stakeholders in the development of social work in Vietnam (i.e. policy‐makers, pioneering educators, and practitioners) had reached a shared understanding about the mission and core values of Vietnamese social work by the end of 2015. An exploratory survey was conducted with 65 participants representing key stakeholders of social work in Vietnam. Participants had a shared but rather generic, at times vague, and overly optimistic view of the mission of Vietnamese social work as a “helping profession” that would be able to solve every social problem and present in all areas. There was a strong, unanimous desire for Vietnamese social work to focus on human dignity, social justice, and individuals’ rights, mixed with the preservation of Vietnam's collective, community‐based culture under the central guiding role of the state.     

语言测试的主要研究范式及其发展趋势

研究范式是指导某一领域研究的本体论、认识论和方法论的立场、观点的总和。社会科学 领域的四大研究范式,即实证主义、后实证主义、批判理论以及建构主义,对包括语言测试在内的社会科 学各学科都有着极其重要的指导作用。由于语言测试的核心活动是测量,因而长期以来,该领域一直受 到实证主义范式的支配。然而近年来,受社会科学领域研究范式发展的影响,语言测试领域的研究范式 也开始呈现出多元化、综合化的特征。但考虑到测试活动的本质属性等因素,实证主义和后实证主义范 式仍将支配这一领域未来的研究 ;而批判理论和建构主义研究范式也将通过与传统范式相结合等方式,对测试研究产生持续的影响。     

杜夫海纳的艺术时空观

杜夫海纳的艺术时空观构成了审美对象自律性的理论基础,成为审美对象"准主体"的重要成因.正是通过建构"时间的空间化"和"空间的时间化"相结合的艺术时空观,杜夫海纳赋予了艺术作品和审美对象独特的存在方式和崭新的地位,从而将审美对象与审美知觉置于可逆双向的审美知觉意向性结构加以考察,实现了审美经验过程的交互主体性,进而揭示了审美对象"准主体"与审美欣赏主体在交感思考中的主体间性亲缘关系.     

白簕叶总黄酮的体外抗氧化活性研究

为研究药用植物白簕的抗氧化性,全文以维生素C(VC)为对照,采用DPPH.清除能力法、铁还原力法和总抗氧化力3种方法,对白簕叶总黄酮的纯化液进行体外抗氧化性实验.结果显示:白簕黄酮纯化液的抗氧化性与其浓度相关性大.在一定剂量范围内,抗氧化性随着纯化液浓度的增大而加强;但到某一水平时,随纯化液浓度的增加,抗氧化力变化微小.总体来讲,浓度选用45mg/mL抗氧化效果较好.白簕总黄酮纯化液抗氧化性明显强于VC.该实验结果对于应用白簕作为新型抗氧化剂,如何控制好黄酮使用量的研究提供了理论依据.