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In September 2018, Hurricane Florence caused widespread and extended school closures throughout North Carolina. Leveraging variation within schools over time, we explore heterogeneity in the impact of hurricane-related schooling disruption on students’ end-of-grade test scores. Impacts were not concentrated on students performing at the lowest levels in the prior year nor on those from the most disadvantaged backgrounds. Rather, the estimates suggest that most students experienced small declines in test performance irrespective of baseline human capital or demographic group. 相似文献
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Previous literature has shown that task-based goal-setting and distributed learning is beneficial to university-level course performance. We investigate the effects of making these insights salient to students by sending out goal-setting prompts in a blended learning environment with bi-weekly quizzes. The randomized field experiment in a large mandatory economics course shows promising results: the treated students outperform the control group. They are 18.8% (0.20 SD) more likely to pass the exam and earn 6.7% (0.19 SD) more points on the exam. While we cannot causally disentangle the effects of goal-setting from the prompt sent, we observe that treated students use the online learning platform earlier in the semester and attempt more online exercises compared to the control group. The heterogeneity analysis suggests that higher treatment effects are associated with low performance at the beginning of the course. 相似文献
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It is well known that sliding mode control is based on the definition of an invariant manifold, where the system dynamics are forced to in a finite time. Such a manifold is somewhat arbitrarily defined, as long as the system dynamics are stable on it. Computational and control effort may vary depending on selected manifold. Obviously, if a system has naturally acceptable stable dynamics around a desired equilibrium point, no control is needed unless uncertainties or disturbances are present. It would be desirable that if such a system had uncertainties or disturbances, the control effort be designed only to overcome the effect of such factors. For a system with first order dynamics and affine control input, designing a sliding mode control overcoming only such uncertainties or disturbances is a trivial task. When a higher order dynamics system is involved, unit control may be used, where the input control signals are not discontinuous, but when only discontinuous control inputs are available, a design approach is not readily available. In this paper, taking advantage of the natural stable dynamics of a system, a sliding mode control approach is introduced for designing multiple discontinuous control inputs, where the control effort overcomes only uncertainties, disturbances or unstable dynamics. Two illustrative examples are given in order to show the feasibility of the method. 相似文献
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作者通过对四川省青川县和彭州市两个地震灾区6-24个月龄婴幼儿健康状况的统计分析,发现该地区生长发育状况不佳,存在营养不良现象,其中贫血率较高。经过对比进行营养包6个月干预后的人群统计分析,发现营养状况稍得到改善,其中彭州市目标人群贫血改善明显,由此提出面对四川其它或其它类似贫困地震地区,由于贫困,天灾必然加剧受灾人群的营养状况,特别是贫血率状况,针对这些地区的求援,必须紧迫加强营养包的干预,而且需要持续性的干预,比较可靠的预算应该在灾难期6个月以上方有一定的作用,同时必要的管理措施有利于保证营养干预对象的稳定性,提高营养干预的有效性的。 相似文献
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实验课对天然药物化学教学有着关键性影响,在其中引入设计性实验教学是对现有实验课程的一次探索性改革。设计性实验教学方案的构建和实施需要从课题选择、方案设计、实验准备、实验实施及结果分析等多个环节入手,在教学实践中这种教学方式取得了良好的效果。 相似文献
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《Information processing & management》2022,59(5):103028
Assigning paper to suitable reviewers is of great significance to ensure the accuracy and fairness of peer review results. In the past three decades, many researchers have made a wealth of achievements on the reviewer assignment problem (RAP). In this survey, we provide a comprehensive review of the primary research achievements on reviewer assignment algorithm from 1992 to 2022. Specially, this survey first discusses the background and necessity of automatic reviewer assignment, and then systematically summarize the existing research work from three aspects, i.e., construction of candidate reviewer database, computation of matching degree between reviewers and papers, and reviewer assignment optimization algorithm, with objective comments on the advantages and disadvantages of the current algorithms. Afterwards, the evaluation metrics and datasets of reviewer assignment algorithm are summarized. To conclude, we prospect the potential research directions of RAP. Since there are few comprehensive survey papers on reviewer assignment algorithm in the past ten years, this survey can serve as a valuable reference for the related researchers and peer review organizers. 相似文献
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《Information processing & management》2022,59(4):102992
Structured sentiment analysis is a newly proposed task, which aims to summarize the overall sentiment and opinion status on given texts, i.e., the opinion expression, the sentiment polarity of the opinion, the holder of the opinion, and the target the opinion towards. In this work, we investigate a transition-based model for end-to-end structured sentiment analysis task. We design a transition architecture which supports the recognition of all the possible opinion quadruples in one shot. Based on the transition backbone, we then propose a Dual-Pointer module for more accurate term boundary detection. Besides, we further introduce a global graph reasoning mechanism, which helps to learn the global-level interactions between the overlapped quadruples. The high-order features are navigated into the transition system to enhance the final predictions. Extensive experimental results on five benchmarks demonstrate both the prominent efficacy and efficiency of our system. Our model outperforms all baselines in terms of all metrics, especially achieving a 10.5% point gain over the current best-performing system only detecting the holder-target-opinion triplets. Further analyses reveal that our framework is also effective in solving the overlapping structure and long-range dependency issues. 相似文献
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为丰富从获取科研基金角度分析我国高校院所药学科研竞争力的研究,基于2005-2019年间国家自然科学基金(NSFC)在药物学、药理学领域有关资助数据,从获取科研经费、基金项目负责人数量等维度构建改进的药学学科科研竞争力指数(PSCI),以国内设有药学一级学科博士学位授权点的48家高校院所为实证对象,分析其药学学科科研资助情况、科研竞争力及变化趋势。结果显示:NSFC在药物学、药理学领域资助以面上项目和青年科学基金项目为主,资助项目数量和经费均呈现出先快速增长后平稳发展的态势,表明我国药物学与药理学领域基础研究水平已达一定高度;药学科研竞争力强的单位主要集中在东部沿海和北部沿海综合经济区;高校院所药学科研竞争力位次呈固化趋势,科研资源聚集现象显著。 相似文献