Efficiency and input congestion of major marine transport companies in the world

The marine transport companies have been experiencing intense competition with the supply increasing faster than the demand, making most of them face input congestion. This paper applies the input congestion data envelopment analysis (DEA) model proposed by Tone and Sahoo (2004) to compute efficiency scores and input congestions of 159 major marine transport companies in the world during 2010-2019. The inputs include em-ployees, total assets, and capital whereas the output is net sales. The base year for monetary values is 2010. It is found that the annual ratios of input-congested marine companies are between 20.9% and 65.7%, indicating that input congestion is not an unusual phenomenon among these companies. This paper also applies a BCG-like analysis to consider inefficiency and input congestion at the same time. The Mann-Whitney U test shows that most of the marine transport companies in Asia, Europe, and the Americas face both inefficiency and input congestion problems during the data period. This analysis is able to provide the implications for shipping companies to conduct more precise and efficient resource allocation and coordination in the post Covid-19 era.

Evaluation of Long-Term Modeling Fine Particulate Matter and Ozone in China During 2013-2019

Air quality in China has been undergoing significant changes due to the implementation of extensive emission control measures since 2013. Many observational and modeling studies investigated the formation mechanisms of fine particulate matter (PM2.5) and ozone (O-3) pollution in the major regions of China. To improve understanding of the driving forces for the changes in PM2.5 and O-3 in China, a nationwide air quality modeling study was conducted from 2013 to 2019 using the Weather Research and Forecasting/Community Multiscale Air Quality (WRF/CMAQ) modeling system. In this study, the model predictions were evaluated using the observation data for the key pollutants including O-3, sulfur dioxide (SO2), nitrogen dioxide (NO2), and PM2.5 and its major components. The evaluation mainly focused on five major regions, that is , the North China Plain (NCP), the Yangtze River Delta (YRD), the Pearl River Delta (PRD), the Chengyu Basin (CY), and the Fenwei Plain (FW). The CMAQ model successfully reproduced the air pollutants in all the regions with model performance indices meeting the suggested benchmarks. However, over-prediction of PM2.5 was noted in CY. NO2, O-3,O- and PM2.5 were well simulated in the north compared to the south. Nitrate (NO3-) and ammonium (NH4+) were the most important PM2.5 components in heavily polluted regions. For the performance on different pollution levels, the model generally over-predicted the clean days but underpredicted the polluted days. O-3 was found increasing each year, while other pollutants gradually reduced during 2013-2019 across the five regions. In all of the regions except PRD (all seasons) and YRD (spring and summer), the correlations between PM2.5 and O-3 were negative during all four seasons. Low-to-medium correlations were noted between the simulated PM2.5 and NO2, while strong and positive correlations were established between PM2.5 and SO2 during all four seasons across the five regions. This study validates the ability of the CMAQ model in simulating air pollution in China over a long period and provides insights for designing effective emission control strategies across China.

Immunogenicity and safety of a SARS-CoV-2 inactivated vaccine in healthy adults: randomized, double-blind, and placebo-controlled phase 1 and phase 2 clinical trials

BACKGROUND: The significant morbidity and mortality resulted from the infection of a severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) call for urgent development of effective and safe vaccines. We report the immunogenicity and safety of an inactivated SARS-CoV-2 vaccine, KCONVAC, in healthy adults. METHODS: Phase 1 and phase 2 randomized, double-blind, and placebo-controlled trials of KCONVAC were conducted in healthy Chinese adults aged 18-59 years. The participants in the phase 1 trial were randomized to receive two doses, one each on Days 0 and 14, of either KCONVAC (5 mug/dose or 10 mug/dose) or placebo. The participants in the phase 2 trial were randomized to receive either KCONVAC (at 5 or 10 mug/dose) or placebo on Days 0 and 14 (0/14 regimen) or Days 0 and 28 (0/28 regimen). In the phase 1 trial, the primary safety endpoint was the proportion of participants experiencing adverse reactions/events within 28 days following the administration of each dose. In the phase 2 trial, the primary immunogenicity endpoints were neutralization antibody seroconversion and titer and anti-receptor-binding domain immunoglobulin G seroconversion at 28 days after the second dose. RESULTS: In the phase 1 trial, 60 participants were enrolled and received at least one dose of 5-mug vaccine (n = 24), 10-mug vaccine (n = 24), or placebo (n = 12). In the phase 2 trial, 500 participants were enrolled and received at least one dose of 5-mug vaccine (n = 100 for 0/14 or 0/28 regimens), 10-mug vaccine (n = 100 for each regimen), or placebo (n = 50 for each regimen). In the phase 1 trial, 13 (54%), 11 (46%), and 7 (58%) participants reported at least one adverse event (AE) after receiving 5-mug vaccine, 10-mug vaccine, or placebo, respectively. In the phase 2 trial, 16 (16%), 19 (19%), and 9 (18%) 0/14-regimen participants reported at least one AE after receiving 5-mug vaccine, 10-mug vaccine, or placebo, respectively. Similar AE incidences were observed in the three 0/28-regimen treatment groups. No AEs with an intensity of grade 3+ were reported, expect for one vaccine-unrelated serious AE (foot fracture) reported in the phase 1 trial. KCONVAC induced significant antibody responses;0/28 regimen showed a higher immune responses than that did 0/14 regimen after receiving two vaccine doses. CONCLUSIONS: Both doses of KCONVAC are well tolerated and able to induce robust immune responses in healthy adults. These results support testing 5-mug vaccine in the 0/28 regimen in an upcoming phase 3 efficacy trial. TRIAL REGISTRATION: http://www.chictr.org.cn/index.aspx (No. ChiCTR2000038804, http://www.chictr.org.cn/showproj.aspx?proj=62350;No. ChiCTR2000039462, http://www.chictr.org.cn/showproj.aspx?proj=63353).

Driving Forces of Changes in Air Quality during the COVID-19 Lockdown Period in the Yangtze River Delta Region, China

During the COVID-19 lockdown period (from January 23 to February 29, 2020), ambient PM2.5 concentrations in the Yangtze River Delta (YRD) region were observed to be much lower, while the maximum daily 8 h average (MDA8) O-3 concentrations became much higher compared to those before the lockdown (from January 1 to 22, 2020). Here, we show that emission reduction is the major driving force for the PM2.5 change, contributing to a PM2.5 decrease by 37% to 55% in the four YRD major cities (i.e., Shanghai, Hangzhou, Nanjing, and Hefei), but the MDA8 O-3 increase is driven by both emission reduction (29%-52%) and variation in meteorological conditions (17%-49%). Among all pollutants, reduction in emissions mainly of primary PM contributes to a PM2.5 decrease by 28% to 46%, and NOx emission reduction contributes 7% to 10%. Although NOx emission reduction dominates the MDA8 O-3 increase (38%-59%), volatile organic compounds (VOCs) emission reduction lead to a 5% to 9% MDA8 O-3 decrease. Increased O-3 promotes secondary aerosol formation and partially offsets the decrease of PM2.5 caused by the primary PM emission reductions. The results demonstrate that more coordinated air pollution control strategies are needed in YRD.

[Construction of urban scale-free network model and its epidemiological significance in the prevention and control of COVID-19].

COVID-19 is a public health emergency currently. In this study, a scale-free network model is established based on the Spring Migration data in 2020.The cities is clustered into three different modules. The epidemic of the cities in the black module was the most serious, followed by the red and the cyan. The black module contains 9 cities in Zhejiang province and 8 cities in Guangdong province, most of them located in the southeast coastal economic belt. These cities should be the key cities for epidemic prevention and control.