高水平乒乓球运动员有力臂最大等长收缩力的评估

乒乓球是使用单侧上肢的一项运动,其特征是要进行重复多次高速且具爆发力的动作,无氧乳酸酵解代谢能力占有重要作用.研究对象与方法男女高水平乒乓球运动员(n=31).采用Takei5101握力计测量单侧上肢有力型和非单侧上肢有力型运动员的上肢最大等长收缩力.18名男运动员(平均年龄23.5±5.4岁)和13名女运动员(平均年龄21.3±3.3岁)均为西班牙乒乓球协会的国家联盟成员.采用SPSS v12.0 for windows和Excel v10.2软件包进行数据统计分析.研究结果发现无论男女运动员单侧上肢有力型的最大等长收缩力均高于非单侧上肢有力型,而左势手女运动员与右势手女运动员相比、右势手男运动员与左势手男运动员相比,单侧上肢有力型的最大等长收缩力均高于非单侧上肢有力型.研究还发现进攻型运动员与防守型运动员相比,单侧上肢有力型的最大等长收缩力高于非单侧上肢有力型.分析与讨论无论男女,单侧上肢有力型运动员手握力高于非单侧上肢有力型运动员.男性运动员比女性运动员的等长收缩力高,一个可以解释的事实是男性有更高的睾酮水平.肌肉力量不平衡可能发展成为脊柱侧弯姿态,这应该通过适当的力量和柔韧性训练来避免,以防止将来的运动损伤和运动成绩的下降.     

Pedagogical differences during a science and language intervention for English language learners

The purpose of this study was to compare and describe 8 fifth-grade classrooms by their teachers pedagogy during a quasiexperimental, longitudinal, and field-based project focused on increasing English language learners' (ELLs') achievement in science and language. The larger study found statistically significant and positive intervention effects in favor of the treatment group on measures of science and language achievement. This study adds an in-depth analysis of the teacher pedagogical practices contributing to students' science and language achievement as captured by an observational instrument used during the project. Results from the analysis show how treatment teachers, when compared to control teachers, focused on activities promoting verbal and written interaction among the students and dense cognitive language use during science inquiry instruction. The findings support the importance of effectively using language in the science classroom to improve ELLs' science and language achievement. Implications for future research and practice are discussed.     

Topological metrics in academic genealogy graphs

Academic genealogy aims to structure and analyze the mentoring relationships between advisor and advisee. The representation of this structure results in academic genealogy graphs. For the analysis and characterization of these graphs, we present a set of metrics and their corresponding mirror metrics that capture the characteristics of its topological structure and represent them as quantitative attributes. The metrics of fecundity, fertility, descendants, cousins, generations, and relationships consider the descendants of the academics represented in the graph. The mirror metric of these topological metrics considers the ascendancy of academics. Individually, the metrics have strong semantic intuition and define characteristics regarding the performance in the mentoring of an academic. Together, the metrics are useful for the identification, characterization, and classification of communities and their members. The genealogical data available through the platforms of the Mathematics Genealogy Project and the Academic Family Tree were used as case studies. Two hundred thirteen thousand and 675,000 academic records were obtained for each project. We analyze the capacity of characterization of the metrics using the structuring of a similarity graph and through the distribution of the nodes in principal components. We observed that the set of metrics is capable of capturing the configuration pattern existing in genealogy graphs independently of its scale.     

Open-domain conversational search assistants: the Transformer is all you need

Information Retrieval Journal - On the quest of providing a more natural interaction between users and search systems, open-domain conversational search assistants have emerged, by assisting users...     

技术革命对图书馆的影响

介绍技术革命对发达国家图书馆影响的文章近几年很多,但以翻译介绍、表层描述和理论阐释为多。最近,应邀在上海图书馆访问的 Gomez 先生,以美国基层公共图书馆馆长的身份,从实践工作的角度,论述了技术革命对美国图书馆的影响。本刊特选载他的这次!演讲,以期有助于国内同仁更全面地认识这个关系到图书馆生存发展的重大问题。注重理论联系实际是本刊的一贯宗旨,我们热切期望有更多的紧密联系各馆实际的好文章问世,推动图书馆现代化研究的进一步深入。     

Determinants of possession of the ball in soccer

In research on the importance of the possession of the ball in soccer, little attention has been paid to its determinants. Using data from 170 matches of the 2003 - 2004 Spanish Soccer League, we explain why differences in the possession of the ball among teams are so great. In particular, four variables are examined: evolving match status (i.e. whether the team is winning, losing or drawing), venue (i.e. playing at home or away), and the identities of the team and the opponent in each match. Results of linear regression analysis show that these four variables are statistically significant and together explain most of the variance in possession. In short, home teams have more possession than away teams, teams have more possession when they are losing matches than when winning or drawing, and the identity of the opponent matters - the worse the opponent, the greater the possession of the ball. Combinations of these variables could be used to develop a model that predicts possession in soccer.     

Natural language processing to identify the creation and impact of new technologies in patent text: Code,data, and new measures

We develop natural language processing techniques to identify the creation and impact of new technologies in the population of U.S. patents. We validate the new techniques and their improvement over traditional metrics based on patent classification and citations in two case-control studies. First, we collect patents linked to awards such as the Nobel prize and the National Inventor Hall of Fame. These patents likely cover radically new technologies with a major impact on technological progress and patenting. Second, we identify patents granted by the United States Patent and Trademark Office but simultaneously rejected by both the European and Japanese patent office. Such patents arguably lack novelty or cover small incremental advances over prior art and should have little impact on technological progress. We provide open access to code, data, and new measures for all utility patents granted by the USPTO up to May 2018 (see https://zenodo.org/record/3515985, DOI: 10.5281/zenodo.3515985).