心理学的遗忘理论对二语损耗的解释力

语言损耗经过三十年的发展,取得了许多有价值的研究成果。在回顾二语损耗研究的基础上,运用心理学遗忘理论中的提取变慢说（或提取失败说）、干扰说以及遗忘曲线,通过对国内外的二语损耗研究结果进行解释,发现提取速度变慢说（或提取失败说）可以解释二语损耗研究中受损者在产出性技能损耗方面的表现以及产出性技能与接受性技能在损耗方面的差异;干扰说可以解释二语损耗研究中受损者在音素、词汇以及形态-句法等方面的损耗。但是,遗忘曲线却无法解释二语损耗研究中出现的＂最初的稳定状态＂现象与二语损耗的倒置假设。     

On Efficiency of Multilevel Splitting

This article focuses on estimating rare events using multilevel splitting schemes. The event of interest is that a Markov process enters some rare set before another (“tabu”) set. It is known that in this setting a large deviations analysis is not always sufficient for constructing asymptotically efficient importance sampling schemes; additional modifications to the change of measure suggested by large deviations are needed. As an alternative, we design an asymptotically efficient multilevel splitting scheme that relies on the large deviations analysis only. This property makes it more flexible and easier to implement than corresponding importance sampling schemes.     

基于中心-外围模型的产业转移滞缓成因及对策研究

从新经济地理学角度切入,在中心-外围理论模型基础上进行拓展,引入要素资源禀赋系数作为参数,对模型进行数值模拟,以便找出导致产业转移滞缓的关键因素.结论表明:要素资源禀赋、运输成本以及劳动力价格仍是影响产业转移的重要因素;我国东部制造业尚未达到产业转移的内生临界点.最后,对产业转移提出一些合理的政策建议.     

The snowball effect of customer slowdown in critical many-server systems

Customer slowdown describes the phenomenon that a customer’s service requirement increases with experienced delay. In healthcare settings, there is substantial empirical evidence for slowdown, particularly when a patient’s delay exceeds a certain threshold. For such threshold slowdown situations, we design and analyze a many-server system that leads to a two-dimensional Markov process. Analysis of this system leads to insights into the potentially detrimental effects of slowdown, especially in heavy-traffic conditions. We quantify the consequences of underprovisioning due to neglecting slowdown, demonstrate the presence of a subtle bistable system behavior, and discuss in detail the snowball effect: A delayed customer has an increased service requirement, causing longer delays for other customers, who in turn due to slowdown might require longer service times.