Based on the fourth-wave Beijing College Students Panel Survey(BCSPS),this study aims to provide accurate estimation of the percentage of the potential sexual minorities among the Beijing college students by using mac...Based on the fourth-wave Beijing College Students Panel Survey(BCSPS),this study aims to provide accurate estimation of the percentage of the potential sexual minorities among the Beijing college students by using machine learning methods.Specifically,we employ random forest(RF),an ensemble learning approach for classification and regression,to predict the sexual orientation of those who were not willing to disclose his/her inherent sexual identity.To overcome the imbalance problem arising from far different numerical proportion of sexual minority and majority members,we adopt the repeated random sub-sampling for training set by partitioning those who expressed heterosexual orientation into different number of splits and further combining each split with those who expressed sexual minority orientation.The prediction from 24-split random forest suggests that youths in Beijing with sexual minority orientation amount to 5.71%,almost two times that of the original estimation 3.03%.The results are robust to alternative learning methods and covariate sets.Besides,it is also suggested that random forest outperforms other learning algorithms,including AdaBoost,Naïve Bayes,support vector machine(SVM),and logistic regression,in dealing with missing data,by showing higher accuracy,F1 score,and area under curve(AUC)value.展开更多
Here, a rhodium(Ⅲ)-catalyzed benzo[c]azepine-1,3(2 H)-dione synthesis via tandem C-H alkylation and intramolecular amination of N-methoxylbenzamide with 3-bromo-3,3-difluoropropene as the alkylation agent is reported...Here, a rhodium(Ⅲ)-catalyzed benzo[c]azepine-1,3(2 H)-dione synthesis via tandem C-H alkylation and intramolecular amination of N-methoxylbenzamide with 3-bromo-3,3-difluoropropene as the alkylation agent is reported. The substituted benzamides and protected indoles are all tolerated, yielding the corresponding products in moderate to good yields. Further study revealed those bioactive compounds such as piperic acid and a key precursor of Roflumilast all perform well, highlighting the synthetic utility of this method.展开更多
Destination familiarity is an important non-economic determinant of tourists’destination choice that has not been adequately studied.This study posits a literary dimension to the concept of destination familiarity—t...Destination familiarity is an important non-economic determinant of tourists’destination choice that has not been adequately studied.This study posits a literary dimension to the concept of destination familiarity—that is,the extent to which tourists have gained familiarity with a given destination through literature—and seeks to investigate the impact of this form of familiarity on inbound tourism to China's Mainland.Employing the English fiction dataset of the Google Books corpus,the New York Times annotated corpus,and the Time magazine corpus,we construct two types of destination familiarity based on literary texts:affectionbased destination familiarity and knowledge-based destination familiarity.The results from dynamic panel estimation(1994–2004)demonstrate that the higher the degree of affection-based destination familiarity with a province in the previous year,the larger the number of inbound tourists the following year.Examining the influence of literature and its consumption on tourism activities sheds light on the dynamics of sustainable tourism development in emerging markets.展开更多
文摘Based on the fourth-wave Beijing College Students Panel Survey(BCSPS),this study aims to provide accurate estimation of the percentage of the potential sexual minorities among the Beijing college students by using machine learning methods.Specifically,we employ random forest(RF),an ensemble learning approach for classification and regression,to predict the sexual orientation of those who were not willing to disclose his/her inherent sexual identity.To overcome the imbalance problem arising from far different numerical proportion of sexual minority and majority members,we adopt the repeated random sub-sampling for training set by partitioning those who expressed heterosexual orientation into different number of splits and further combining each split with those who expressed sexual minority orientation.The prediction from 24-split random forest suggests that youths in Beijing with sexual minority orientation amount to 5.71%,almost two times that of the original estimation 3.03%.The results are robust to alternative learning methods and covariate sets.Besides,it is also suggested that random forest outperforms other learning algorithms,including AdaBoost,Naïve Bayes,support vector machine(SVM),and logistic regression,in dealing with missing data,by showing higher accuracy,F1 score,and area under curve(AUC)value.
基金supported by the Natural Science Foundation of China (No.21772139)the Jiangsu Province Natural Science Found for Distinguished Young Scholars (No.BK20180041)+1 种基金the PAPD Projectsupported by the Open Research Fund of the School of Chemistry and Chemical Engineering,Henan Normal University。
文摘Here, a rhodium(Ⅲ)-catalyzed benzo[c]azepine-1,3(2 H)-dione synthesis via tandem C-H alkylation and intramolecular amination of N-methoxylbenzamide with 3-bromo-3,3-difluoropropene as the alkylation agent is reported. The substituted benzamides and protected indoles are all tolerated, yielding the corresponding products in moderate to good yields. Further study revealed those bioactive compounds such as piperic acid and a key precursor of Roflumilast all perform well, highlighting the synthetic utility of this method.
基金This work was supported in part by the Tsinghua University Initiative Scientific Research Program(No.2019THZWLJ29).
文摘Destination familiarity is an important non-economic determinant of tourists’destination choice that has not been adequately studied.This study posits a literary dimension to the concept of destination familiarity—that is,the extent to which tourists have gained familiarity with a given destination through literature—and seeks to investigate the impact of this form of familiarity on inbound tourism to China's Mainland.Employing the English fiction dataset of the Google Books corpus,the New York Times annotated corpus,and the Time magazine corpus,we construct two types of destination familiarity based on literary texts:affectionbased destination familiarity and knowledge-based destination familiarity.The results from dynamic panel estimation(1994–2004)demonstrate that the higher the degree of affection-based destination familiarity with a province in the previous year,the larger the number of inbound tourists the following year.Examining the influence of literature and its consumption on tourism activities sheds light on the dynamics of sustainable tourism development in emerging markets.