arXiv subjects

Xiaojing Cai

Publications and source records attributed to Xiaojing Cai.

5 recordsLinked to original sources

arXiv2026

Network Evolution and National Interests: Global Scientific Reorganization and the Rise of Scientific Nationalism

The global network of scientific cooperation has undergone major restructuring over the past two decades, with important implications for geopolitics and science policy. China's integration into this network has redistributed positions of influence in ways that challenge zero-sum views of national competition and security. Drawing on structural holes theory and the Bianconi-Barabasi fitness model, we argue that China's entry accelerated an ongoing process of network maturation. As China's scientific capacity expanded, it formed direct collaborations that reduced reliance on U.S. intermediation. Network analysis shows a large decline in U.S. betweenness centrality, while weighted measures remain stable, indicating a loss of brokerage advantages but continued strong bilateral ties. Granger causality tests suggest that China's early participation predicted later structural changes across fields. Results are consistent across six major domains.

stat.OT↗

arXiv2025

Optimal vs. Naive Diversification in the Cryptocurrencies Market: The Role of Time-Varying Moments and Transaction Costs

This study investigates three central questions in portfolio optimization. First, whether time-varying moment estimators outperform conventional sample estimators in practical portfolio construction. Second, whether incorporating a turnover penalty into the optimization objective can improve out-of-sample performance. Third, what type of optimal portfolio strategies can consistently outperform the naive 1/N benchmark. Using empirical evidence from the cryptocurrencies market, this paper provides comprehensive answers to these questions. In the process, several additional findings are uncovered, offering further insights into the dynamics of portfolio construction in highly volatile asset classes.

q-fin.PM↗

arXiv2024

State Level Representation of Chinese Scholars Mobility to and within the United States, 2009 to 2018

A review of researcher mobility between China and the United States shows overall growth in mobility between the two nations. A review based upon a scholarâ€™s change of address from China to the United States or vice versa reveals mobility patterns. Between 2009 and 2018, an overall upward trend is noted for incoming scholars from China, as well as upward trends in those returning to China. Within the United States, researchers flow across states, but they are less likely to leave the larger, more R&D-rich states like California, New York, or Massachusetts. Chinese researchers are more likely to locate based upon reputation of research institutions than overall research spending or defense research locations. Mobility has a positive impact on China-U.S. collaboration numbers and citations.

physics.soc-ph↗

arXiv2022

Changes in co-publication patterns among China, the European Union (28) and the United States of America, 2016-2021

The COVID-19 global pandemic starting in January 2020 disrupted international collaborations in scholarly exchange, reducing mobility and connections across the globe. An examination of Web of Science-indexed publications from China, the European Union-28 and the United States of America shows a drop in publications numbers coming from the EU-28 and the United States in 2021. Importantly, cooperation between China and the United States drops without a corresponding drop between China and the EU-28. Moreover, the drop in China-USA cooperation can be seen beginning in 2019, before the pandemic, at a time when political tensions around science, technology, and innovation arose, with the United States claiming that China was violating intellectual property norms. The patterns suggest that political tensions, more than the pandemic, influenced the drop in China-USA cooperation.

cs.DL↗

arXiv2022

One-Year In: COVID-19 Research at the International Level in CORD-19 Data

The appearance of a novel coronavirus in late 2019 radically changed the community of researchers working on coronaviruses since the 2002 SARS epidemic. In 2020, coronavirus-related publications grew by 20 times over the previous two years, with 130,000 more researchers publishing on related topics. The United States, the United Kingdom and China led dozens of nations working on coronavirus prior to the pandemic, but leadership consolidated among these three nations in 2020, which collectively accounted for 50% of all papers, garnering well more than 60% of citations. China took an early lead on COVID-19 research, but dropped rapidly in production and international participation through the year. Europe showed an opposite pattern, beginning slowly in publications but growing in contributions during the year. The share of internationally collaborative publications dropped from pre-pandemic rates; single-authored publications grew. For all nations, including China, the number of publications about COVID track closely with the outbreak of COVID-19 cases. Lower-income nations participate very little in COVID-19 research in 2020. Topic maps of internationally collaborative work show the rise of patient care and public health clusters, two topics that were largely absent from coronavirus research in the two years prior to 2020. Findings are consistent with global science as a self-organizing system operating on a reputation-based dynamic.

cs.DL↗