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Lee K Kim C Young Yang J Lee H Ahn B Xu L Yoon Kang J Oh KW 《Biomicrofluidics》2012,6(1):14114-141147
We propose a simple method for forming massive and uniform three-dimensional (3-D) cell spheroids in a multi-level structured microfluidic device by gravitational force. The concept of orienting the device vertically has allowed spheroid formation, long-term perfusion, and retrieval of the cultured spheroids by user-friendly standard pipetting. We have successfully formed, perfused, and retrieved uniform, size-controllable, well-conditioned spheroids of human embryonic kidney 293 cells (HEK 293) in the gravity-oriented microfluidic device. We expect the proposed method will be a useful tool to study in-vitro 3-D cell models for the proliferation, differentiation, and metabolism of embryoid bodies or tumours. 相似文献
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在线商品虚假评论信息不仅误导消费者购物决策与商家销售评估,而且严重干扰了在线商品交易平台的意见挖掘结果。本文针对国内外对在线商品虚假评论治理的研究现状,从法律监管和鉴别模型两个层面重新定位了其治理目标,指出应根据不同的治理对象,从监管虚假评论形成路径的基本要素、减弱虚假评论形成路径的促进因素、激励正常消费者作出真实有效的评论并优化虚假评论识别模型的鉴别准确率4个方面完善在线商品虚假评论信息的治理途径,并详细阐述了各治理途径的具体实施办法以及今后优化和完善的建议与对策。 相似文献
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国内外政务社交媒体研究评述及展望 总被引:1,自引:0,他引:1
[目的/意义] 本研究对国内外政务社交媒体相关研究进行梳理,分析现有研究的特点及不足,以期为政务社交媒体研究提供参考和借鉴。[方法/过程] 通过文献调研,对2014-2019年的国内外政务社交媒体研究进行系统归纳,梳理现有研究的特点及不足,以期为政务社交媒体研究提供参考和借鉴。[结果/总结] 分析发现近年的政务社交媒体研究多为量化研究,分析方法包括内容分析法、统计分析法、社会网络分析法、机器学习方法,研究主题集中于政务社交媒体的运营管理、内容挖掘、应急管理、功能与作用。现有研究存在着数据来源较为单一、数据分析方法有待优化、缺乏系统规范的研究范式等方面的不足,并从政府和公众两个视角为政务社交媒体的未来研究提供思路。 相似文献
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Emmanouil Amolochitis Ioannis T. Christou Zheng-Hua Tan Ramjee Prasad 《Information processing & management》2013
We present PubSearch, a hybrid heuristic scheme for re-ranking academic papers retrieved from standard digital libraries such as the ACM Portal. The scheme is based on the hierarchical combination of a custom implementation of the term frequency heuristic, a time-depreciated citation score and a graph-theoretic computed score that relates the paper’s index terms with each other. We designed and developed a meta-search engine that submits user queries to standard digital repositories of academic publications and re-ranks the repository results using the hierarchical heuristic scheme. We evaluate our proposed re-ranking scheme via user feedback against the results of ACM Portal on a total of 58 different user queries specified from 15 different users. The results show that our proposed scheme significantly outperforms ACM Portal in terms of retrieval precision as measured by most common metrics in Information Retrieval including Normalized Discounted Cumulative Gain (NDCG), Expected Reciprocal Rank (ERR) as well as a newly introduced lexicographic rule (LEX) of ranking search results. In particular, PubSearch outperforms ACM Portal by more than 77% in terms of ERR, by more than 11% in terms of NDCG, and by more than 907.5% in terms of LEX. We also re-rank the top-10 results of a subset of the original 58 user queries produced by Google Scholar, Microsoft Academic Search, and ArnetMiner; the results show that PubSearch compares very well against these search engines as well. The proposed scheme can be easily plugged in any existing search engine for retrieval of academic publications. 相似文献
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Referees in German first-league soccer games do not award as many yellow cards in the beginning of a game as should be statistically expected. One explanation for this effect is the concept of game management (Mascarenhas, Collins, & Mortimer, 2002). Alternatively, the consistency model (Haubensak, 1992) explains the effect as a necessity of the judgment situation: Referees need to calibrate a judgment scale, and, to preserve degrees of freedom in that scale, they need to avoid extreme category judgments in the beginning (i.e., yellow cards). Experiment 1 shows that referees who judge scenes in the context of a game award fewer yellow cards than referees who see the same scenes in random order. Experiment 2 shows the combined influence of game management (by explicitly providing information about the game situation) and calibration (early vs. late scenes in the time course of a game). Theoretical implications for expert refereeing and referee training are discussed. 相似文献
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Woo M Kim S Kim J Petruzzello SJ Hatfield BD 《Research quarterly for exercise and sport》2010,81(3):349-359
The "feel better" effect of exercise has been well established, but the optimal intensity needed to elicit a positive affective response is controversial. In addition, the mechanisms underlying such a response are unclear To clarify these issues, female undergraduate students were monitored for electroencephalographic (EEG) and self-reported affective responses during the recovery period following rest, low, moderate, and high intensities of treadmill running, each lasting 30 min. Frontal EEG asymmetry and self-reported vigor scores following exercise at all three intensities were significantly elevated compared to those observed following rest. The results suggest that steady-state aerobic exercise bouts executed at varying intensities induce a similar affective response during the recovery period when assessed at both the behavioral and psychophysiological levels. 相似文献