Mapping Population Distribution with High Spatiotemporal Resolution in Beijing Using Baidu Heat Map Data

Population distribution data with high spatiotemporal resolution are of significant value and fundamental to many application areas, such as public health, urban planning, environmental change, and disaster management. However, such data are still not widely available due to the limited knowledge of complex human activity patterns. The emergence of location-based service big data provides additional opportunities to solve this problem. In this study, we integrated ambient population data, nighttime light data, and building volume data;innovatively proposed a spatial downscaling framework for Baidu heat map data during work time and sleep time;and mapped the population distribution with high spatiotemporal resolution (i.e., hourly, 100 m) in Beijing. Finally, we validated the generated population distribution maps with high spatiotemporal resolution using the highest-quality validation data (i.e., mobile signaling data). The relevant results indicate that our proposed spatial downscaling framework for both work time and sleep time has high accuracy, that the distribution of the population in Beijing on a regular weekday shows "centripetal centralization at daytime, centrifugal dispersion at night" spatiotemporal variation characteristics, that the interaction between the purpose of residents' activities and the spatial functional differences leads to the spatiotemporal evolution of the population distribution, and that China's "surgical control and dynamic zero COVID-19" epidemic policy was strongly implemented. In addition, our proposed spatial downscaling framework can be transferred to other regions, which is of value for governmental emergency measures and for studies about human risks to environmental issues.

Sustained Alleviation and Resolution of Targeted COVID-19 Symptoms with Nirmatrelvir/Ritonavir versus Placebo

Background. Nirmatrelvir with ritonavir (nirmatrelvir/r) is an oral antiviral COVID-19 treatment. We report its efficacy to shorten time to sustained alleviation and resolution of COVID-19 signs/symptoms in nonhospitalized adults with COVID-19 at high risk of severe disease as of primary completion data cut (11 Dec 2021). Methods. In this phase 2/3 double-blind study, eligible adults with confirmed SARS-CoV-2 and <= 5 days (d) of symptoms were randomized 1:1 to nirmatrelvir/r 300 mg/100 mg or placebo (PBO) every 12 hrs for 5 d. Pts logged presence and severity (on 3- or 4-point scales) of prespecified COVID-19 signs/symptoms daily Day 1 (predose) through 28. Times to sustained alleviation and resolution of all targeted signs/ symptoms were assessed, summarized with Kaplan-Meier curves, and compared by treatment by log-rank test. Individual signs/symptoms were compared with descriptive analyses. Results. From Jul-Dec 2021, 2246 pts enrolled;2085 pts (nirmatrelvir/r, n=1039;PBO, n=1046) met criteria for the mITT1 population (<= 5 d of symptom onset, did not/not expected to receive an mAb). More pts achieved sustained alleviation or sustained resolution with nirmatrelvir/r. Shorter median times to sustained alleviation/ resolution were observed with nirmatrelvir/r (13/16 d) vs PBO (15/19 d;Fig 1 & 2). Also, a shorter median time to sustained alleviation was seen in pts treated <= 3 d of symptoms with nirmatrelvir/r (12 d) vs PBO (15 d). The most common symptoms were cough, muscle/body aches, and headache in both groups. The median time to sustained alleviation of cough and headache was 2 d less with nirmatrelvir/r vs PBO. The median time to sustained resolution of muscle aches and shortness of breath was 3 d and 4 d less with nirmatrelvir/r. The proportion of pts with severe signs/symptoms in the nirmatrelvir/r vs PBO group was significantly higher at baseline, but significantly lower after treatment, showing nirmatrelvir/r significantly reduced symptom severity through Day 28 (Fig 3). Pts who were seronegative vs seropositive or had high vs low viral load at baseline achieved faster times to sustained alleviation with nirmatrelvir/r vs PBO. Conclusion. Nirmatrelvir/r treatment reduced duration and severity of COVID-19 symptoms vs PBO in pts at high risk of progressing to severe disease. NCT04960202.

Effect of Nirmatrelvir/Ritonavir versus Placebo on COVID-19-Related Hospitalizations and Other Medical Visits

Background. Nirmatrelvir coadministered with ritonavir (nirmatrelvir/r) is a COVID-19 treatment. This study evaluated nirmatrelvir/r in nonhospitalized, symptomatic adults with COVID-19 at high risk of progressing to severe disease. We report secondary efficacy endpoints associated with COVID-19-related medical visits, including hospitalization details and oxygen support, as of the primary completion data cutoff (Dec 11, 2021). Methods. In this phase 2/3 double-blind, interventional study, adults with confirmed SARS-CoV-2 and symptom onset <= 5 days (d) were randomized 1:1 to receive nirmatrelvir/r 300 mg/100 mg or placebo (PBO) orally every 12 hours for 5 d. COVID-19-related medical visits were collected through Day 28. Oxygen support for COVID-19 and details of COVID-19-related hospitalization, including duration, intensive care unit (ICU) status, and mechanical ventilation, were assessed. Results. Of the 2246 patients (pts) enrolled globally from Jul to Dec2021, 2085 (nirmatrelvir/r, n=1039;PBO, n=1046) started treatment and met criteria for the modified intent-to-treat population (mITT1;<= 5 d of symptom onset, did not/not expected to receive a mAb). Fewer overall COVID-19-related medical visits were reported with nirmatrelvir/r vs PBO (Table 1). In addition to fewer hospitalizations being reported with nirmatrelvir/r (n=8 [0.8%]) vs PBO (n=65 [6.2%]), pts receiving nirmatrelvir/ r had fewer hospitalized d (Table 2), with mean durations of 9.6 (range, 5.0, 16.0) d with nirmatrelvir/r and 11.2 (range, 2.0, 57.0) d with PBO in hospitalized pts. No pts in the nirmatrelvir/r group and 9 pts (0.9%) in PBO group were admitted to the ICU. No pts in the nirmatrelvir/r group received mechanical ventilation vs 3 pts in the PBO group. Fewer other COVID-19-related nonhospital medical visits were reported with nirmatrelvir/r vs PBO (Table 3). In the full analysis set, fewer pts required oxygen therapy for COVID-19 with nirmatrelvir/r (n=9/1120 [0.8%]) vs PBO (n=54/1126 [4.8%]). Conclusion. High-risk adults with symptomatic COVID-19 treated with nirmatrelvir/ r within 5 d of symptom onset had fewer COVID-19-related medical visits and reduced healthcare utilization (no ICU visits, no mechanical ventilation, fewer days in hospital) vs pts receiving PBO. (Table Presented).

Brain Drain or Brain Gain: A Growing Trend of Chinese International Students Returning Home for Development

International education and international student mobility are becoming increasingly popular in the era of globalization, which has triggered discussions on brain drain, brain gain, and brain circulation. Nonetheless, international student mobility has been significantly not only by the outbreak of the COVID-19 pandemic but also by the new geopolitics clearly adversely influencing the diplomatic relationships between China and the USA with its allies in the West. In view of the growing complexity closely related to how international politics affecting international learning and student mobility, there is a reverse trend of Chinese international students choosing to return to China in recent years against the worsening relations between China and some major powers in the West. This chapter sets out against the broader political economy context to examine the intentions of Chinese high-level talents graduating from major universities overseas to return to mainland China to pursue their career development. More specifically, this chapter examines the high-level talents’ overall feelings about China and foreign countries from their perspectives. Special attention is given to high-level talents’ preferred institutions and provinces or regions for their career development. Analyzing the major survey data generated from a research project conducted by Peking University, this chapter discusses policy implications for talent attraction and retention for the GBA. © 2022, The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd.

Contrastive loss on masked face verification

The outbreak of COVID-19 has encouraged people to wear their masks more frequently than ever. However, the absence of much facial information from the masked face will cause failures in many current face recognition and verification functions to recognize the individual's identity. To tackle this problem precisely, our group builds a modified SimCLR model with the contrastive loss that is able to extract similarity features from individuals regardless of whether a mask is worn. From our experiments, we find out that our usage of contrastive loss leads to a large improvement in the testing verification accuracy compared to a baseline model with the commonly used MSE loss. © 2021 IEEE.

State heterogeneity in the associations of human mobility with COVID-19 epidemics in the European Union

Background: Human mobility was associated with epidemic changes of coronavirus disease 2019 (COVID-19) in the countries, where strict public health interventions reduced human mobility and COVID-19 epidemics. But its association with COVID-19 epidemics in the European Union (EU) is unclear. Methods: In this quasi-experimental interrupted time-series study, we modelled trends in human mobility and epidemics of COVID-19 in 27 EU states between January 15 and May 9, 2020. The associations of lockdown-date, and turning points of these trends were assessed. Results: There were 982,332 laboratory-confirmed COVID-19 cases in the EU states (median 7,896, interquartile 1,689 to 25,702 for individual states) during the study-period. COVID-19 and human mobility had 3 trend-segments, including an upward trend in COVID-19 daily incidence and a downward trend in most human mobilities in the middle segment. Compared with the states farther from Italy, the state-wide lockdown dates were more likely linked to turning points of human mobilities in the states closer to Italy, which were also more likely linked to second turning points of COVID-19 epidemics. Among the examined human mobilities, the second turning points in driving mobility and the first turning points in parks mobility were the best factors that connected lockdown dates and COVID-19 epidemics in the EU states closer to Italy. Conclusions: We show state- and mobility-heterogeneity in the associations of public health interventions and human mobility with the changes of COVID-19 epidemics in the EU. These findings may help inform policymakers on the best timing and monitoring-parameters of state-level interventions in the EU.