The COVID-19 lockdown was a typical example of extreme emission reduction,providing an opportunity to study the impact of lockdown measures on air pollution.Particle number concentrations(PNC)originate from direct emi...The COVID-19 lockdown was a typical example of extreme emission reduction,providing an opportunity to study the impact of lockdown measures on air pollution.Particle number concentrations(PNC)originate from direct emissions or through new particle formation events.However,their variations during the lockdown period are under investigation.This study focuses on Luohe,a city on the southern edge of the North China Plain,analyzing the changes in PNC and its sources before,during,and after the COVID-19 lockdown.From March 25^(th)to May 31^(st),2022,real-time PNC measurements were conducted using a Scanning Mobility Particle Sizer for particle size.Results showed an 11.2%decrease in PNC during the lockdown compared to pre-lockdown and a 3.6%decrease compared to post-lockdown,indicating reduced local emissions and weakened regional transportation during the lockdown.Positive Matrix Factorization analysis identified six sources contributing to the total PNC,including photochemical nucleation,aged photochemical nucleation,gasoline vehicle emissions,diesel vehicle emissions,coal and biomass combustion,and secondary aerosols.The significant changes in source emissions indicate a substantially reduced traffic volume after the implementation of lockdown measures(2644.8#/cm^(3),2202.2#/cm^(3),2792.7#/cm^(3)).Concurrently,photochemical nucleation(310.1#/cm^(3),306.3#/cm^(3),393.1#/cm^(3))and photochemical nucleation aging(592.8#/cm^(3),744.1#/cm^(3),810.7#/cm^(3))exhibited increasing trends,while coal/biomass combustion(1656.6#/cm^(3),1586.2#/cm^(3),980.0#/cm^(3))and secondary sources(999.4#/cm^(3),791.1#/cm^(3),804.1#/cm^(3))showed decreasing trends.In summary,the contributions of traffic emissions to PNC highlight the potential for targeted traffic management strategies to improve urban air quality.展开更多
The outbreak of COVID-19 has caused concerns globally.To reduce the rapid transmission of the virus,strict city lockdown measures were conducted in different regions.China is the country that takes the earliest home-b...The outbreak of COVID-19 has caused concerns globally.To reduce the rapid transmission of the virus,strict city lockdown measures were conducted in different regions.China is the country that takes the earliest home-based quarantine for people.Although normal industrial and social activities were suspended,the spread of virus was efficiently controlled.Simultaneously,another merit of the city lockdown measure was noticed,which is the improvement of the air quality.Contamination levels of multiple atmospheric pollutants were decreased.However,in this work,24 and 14 air fine particulate matter(PM_(2.5))samples were continuously collected before and during COVID-19 city lockdown in Linfen(a typical heavy industrial city in China),and intriguingly,the unreduced concentration was found for environmentally persistent free radicals(EPFRs)in PM_(2.5)after normal life suspension.The primary non-stopped coal combustion source and secondary Cu-related atmospheric reaction may have impacts on this phenomenon.The cigarette-based assessment model also indicated possible exposure risks of PM_(2.5)-bound EPFRs during lockdown of Linfen.This study revealed not all the contaminants in the atmosphere had an apparent concentration decrease during city lockdown,suggesting the pollutants with complicated sources and formation mechanisms,like EPFRs in PM_(2.5),still should not be ignored.展开更多
Under the effects of COVID-19 and a number of ongoing lockdown tactics,anxiety symptoms and poor sleep quality have become common mental health issues among college freshmen and are intimately related to their emotion...Under the effects of COVID-19 and a number of ongoing lockdown tactics,anxiety symptoms and poor sleep quality have become common mental health issues among college freshmen and are intimately related to their emotional adaptation.To explore this connection,this study gathered data from a sample of 256 freshmen enrolled in an elite university in China in September 2022.The association between sleep quality,anxiety symptoms,and emotional adaptation was clarified using correlation analysis.Additionally,the mediating function of anxiety symptoms between sleep quality and emotional adaptation was investigated using a structural equation model.The results reveal that:(1)Chinese elite university freshmen who were subjected to prolonged lockdown had poor sleep quality and mild anxiety symptoms;(2)a significant positive correlation between poor sleep quality and anxiety symptoms was identified;(3)anxiety symptoms were found to have a significant negative impact on emotional adaptation;(4)poor sleep quality had a negative impact on emotional adaptation through anxiety symptoms.This research makes a valuable contribution by offering insights into the intricate relationship between sleep quality and emotional adaptation among freshmen in elite Chinese universities during prolonged lockdown conditions,and it is beneficial for schools and educators to further improve school schedules and psychological health initiatives.展开更多
Introduction: The COVID-19 pandemic has affected all professional sectors to varying degrees. It has forced companies to restructure, initiate and promote telework. The aim was to study the impacts of COVID-19 lockdow...Introduction: The COVID-19 pandemic has affected all professional sectors to varying degrees. It has forced companies to restructure, initiate and promote telework. The aim was to study the impacts of COVID-19 lockdown on banking activities in Conakry. Materials and Methods: This was a descriptive cross-sectional study over seven months (from November 25, 2020 to June 27, 2021) and multicentric. It included thirteen of the eighteen banks of the main city of the capital Conakry (Kaloum). We analysed socio-demographic data and occupational characteristics. We paid particular attention to banking activities and medical datas. Results: During our study period, 875 workers met to our criteria, one third of whom were men. The average age was 37.93 ± 9.39 years [22 - 71]. Financial accounters were the most represented and average seniority at the job was 5.35 years. The work schedule was reduced during lockdown but an telework increased (29.8%). On the medical datas, the prevalence of COVID-19 was 20.7%;the lethality rate was 0.6% and the absentee rate 15.6%. The COVID-19 lockdown has deeply impacted the banking activities in Conakry particularly the productivity by a significant decrease in net banking income. Conclusion: Despite the continuity of activities during this pandemic, banks have experienced a reduction in their productivity resulting in a significant decrease in net banking income. These impacts of COVID-19 on the banking sector reflect its impact on the national economy.展开更多
The potential hypotheses for finance research based on social media sentiment revolve around the reliability of investor sentiment expressed on social media and the causal relationship between financial markets and th...The potential hypotheses for finance research based on social media sentiment revolve around the reliability of investor sentiment expressed on social media and the causal relationship between financial markets and this sentiment.The central hypothesis we focus on is derived from the"lie game"played by investors on social media.This study is the first to explore three states of this lie game in the context of the Chinese stock market:the"equilibrium state",the"confusion state",and the"subversion state".Our findings indicate that the"equilibrium"state is the typical state of the lie game,where increased investor sentiment results in more positive market behavior,and higher stock prices lead to increased investor sentiment.We also examine the effect of significant social events,such as the"lockdown in Wuhan"and the"lockdown in Shanghai",on the lie game's outcome.The successful lockdown in Wuhan and the public's opposition to the politicization of COVID-19 reinforced the"equilibrium"state of the game.However,the Shanghai lockdown's failure to promptly halt the spread of COVID-19 led to the intertwining of the economy and COVID-19 in public discourse,shifting the lie game's outcome from an"equilibrium state"to a"subversive state".We emphasize that the"confusion state"and"subversion state"outcomes of the lie game are concerning,and managing public opinion and the externalization of domestic conflicts can help reduce this risk.This study offers a fresh perspective on the traditional issues of investor sentiment reliability and the causal relationship between investor sentiment and stock markets.展开更多
The higher concentration of PM_(10) and PM_(2.5) in the lower atmosphere is severely harmful for human health and it also makes visibility diminution along with weather and climate modifications.The main objective is ...The higher concentration of PM_(10) and PM_(2.5) in the lower atmosphere is severely harmful for human health and it also makes visibility diminution along with weather and climate modifications.The main objective is to find out the spatiotemporal variation and dispersal of PM_(10) and PM_(2.5) along with COVID-19 infection in the dusty city Kolkata.The consecutive two years PM_(10) and PM_(2.5) data of different stations have been obtained from State Pollution Control Board,Govt.of West Bengal.Forward trajectory analysis has been done through HYSPLIT(Hybrid Single Particle Lagrangian Integrated Trajectory)model to find the path and direction of air particles.The result showed that the various meteorological or environmental factors(such as temperature,relative humidity,wind,wind speed,pressure and gusty wind)and geographical location regulate the spatiotemporal variation of PM_(10) and PM_(2.5).These factors like high temperature with relative humidity and strong wind influence to disperse the particulate matters from north to south direction from city to outside during summer in Kolkata metropolitan city.During summer(both pre and lockdown years),the height of particles is extended up to 1000 m owing to active atmospheric ventilation whereas in winter it is confined within 100 m.The HYSPLIT model clearly specified that the particles dispersed from south,south-west to north and north east direction due to strong wind.The constant magnification of PM_(10) and PM_(2.5) in the lower atmosphere leads to greater frequency of COVID-19 infections and deaths.In Kolkata,the one of the crucial reasons of high infection and deaths(COVID-19)is co-morbidity of people.展开更多
To control the spread of COVID-19,rigorous restrictions have been implemented in China,resulting in a great reduction in pollutant emissions.In this study,we evaluated the air quality in the Yangtze River Delta during...To control the spread of COVID-19,rigorous restrictions have been implemented in China,resulting in a great reduction in pollutant emissions.In this study,we evaluated the air quality in the Yangtze River Delta during the COVID-19 lockdown period using satellite and ground-based data,including particle matter(PM),trace gases,water-soluble ions(WSIs) and black carbon(BC).We found that the impacts of lockdown policy on air quality cannot be accurately assessed using MODIS aerosol optical depth(AOD) data,whereas the tropospheric nitrogen dioxide(NO_(2)) vertical column density can well reflect the influences of these restrictions on human activities.Compared to the pre-COVID period,the PM_(2.5),PM_(10),NO_(2),carbon monoxide(CO),BC and WSIs during the lockdown in Suzhou were observed to decrease by 37.2%,38.3%,64.5%,26.1%,53.3% and 58.6%,respectively,while the sulfur dioxide(SO_(2)) and ozone(O_(3)) increased by 1.5% and 104.7%.The WSIs ranked in the order of NO_(3)~->NH_(4)^(+)>SO_(4)^(2-)>Cl~->Ca^(2+)>K^(+)>Mg^(2+)>Na + during the lockdown period.By comparisons with the ion concentrations during the pre-COVID period,we found that the ions NO 3-,NH 4 +,SO_(4)^(2-),Cl~-,Ca^(2+),K^(+) and Na^(+) decreased by 66.3%,48.8%,52.9%,56.9%,57.9% and 76.3%,respectively,during the lockdown,in contrast to Mg^(2+),which increased by 30.2%.The lockdown policy was found to have great impacts on the diurnal variations of Cl~-,SO_(4)^(2-),Na^(+) and Ca^(2+).展开更多
The COVID-19 pandemic has escalated into one of the largest crises of the 21 st Century.The new SARS-CoV-2 coronavirus,responsible for COVID-19,has spread rapidly all around the world.The Spanish Government was forced...The COVID-19 pandemic has escalated into one of the largest crises of the 21 st Century.The new SARS-CoV-2 coronavirus,responsible for COVID-19,has spread rapidly all around the world.The Spanish Government was forced to declare a nationwide lockdown in view of the rapidly spreading virus and high mortality rate in the nation.This study investigated the impact of short-term lockdown during the period from March 15th to April 12th 2020 on the atmospheric levels of CO,SO_(2),PM_(10),O_(3),and NO_(2)over 11 representative Spanish cities.The possible influence of several meteorological factors(temperature,precipitation,wind,sunlight hours,minimum and maximum pressure)on the pollutants'levels were also considered.The results obtained show that the 4-week lockdown had significant impact on reducing the atmospheric levels of NO_(2)in all cities except for the small city of Santander as well as CO,SO_(2),and PM_(10)in some cities,but resulted in increase of O_(3)level.展开更多
Estimating the impacts on PM_(2.5)pollution and CO_(2)emissions by human activities in different urban regions is important for developing efficient policies.In early 2020,China implemented a lockdown policy to contai...Estimating the impacts on PM_(2.5)pollution and CO_(2)emissions by human activities in different urban regions is important for developing efficient policies.In early 2020,China implemented a lockdown policy to contain the spread of COVID-19,resulting in a significant reduction of human activities.This event presents a convenient opportunity to study the impact of human activities in the transportation and industrial sectors on air pollution.Here,we investigate the variations in air quality attributed to the COVID-19 lockdown policy in the megacities of China by combining in-situ environmental and meteorological datasets,the Suomi-NPP/VIIRS and the CO_(2)emissions from the Carbon Monitor project.Our study shows that PM_(2.5)concentrations in the spring of 2020 decreased by 41.87%in the Yangtze River Delta(YRD)and 43.30%in the Pearl River Delta(PRD),respectively,owing to the significant shutdown of traffic and manufacturing industries.However,PM_(2.5)concentrations in the Beijing-Tianjin-Hebei(BTH)region only decreased by 2.01%because the energy and steel industries were not fully paused.In addition,unfavorable weather conditions contributed to further increases in the PM_(2.5)concentration.Furthermore,CO_(2)concentrations were not significantly affected in China during the short-term emission reduction,despite a 19.52%reduction in CO_(2)emissions compared to the same period in 2019.Our results suggest that concerted efforts from different emission sectors and effective long-term emission reduction strategies are necessary to control air pollution and CO_(2)emissions.展开更多
To investigate the characteristics of particulate matter with an aerodynamic diameter less than 2.5μm(PM_(2.5))and its chemical compositions in the Beijing-Tianjin-Hebei(BTH)region of China during the novel coronavir...To investigate the characteristics of particulate matter with an aerodynamic diameter less than 2.5μm(PM_(2.5))and its chemical compositions in the Beijing-Tianjin-Hebei(BTH)region of China during the novel coronavirus disease(COVID-19)lockdown,the ground-based data of PM_(2.5),trace gases,water-soluble inorganic ions,and organic and elemental carbon were analyzed in three typical cities(Beijing,Tianjin,and Baoding)in the BTH region of China from 5-15 February 2020.The PM_(2.5)source apportionment was established by combining the weather research and forecasting model and comprehensive air quality model with extensions(WRF-CAMx).The results showed that the maximum daily PM_(2.5)concentration reached the heavy pollution level(>150μg/m^(3))in the above three cities.The sum concentration of SO_(4)^(2-),NO_(3)^(-)and NH_(4)^(+)played a dominant position in PM_(2.5)chemical compositions of Beijing,Tianjin,and Baoding;secondary transformation of gaseous pollutants contributed significantly to PM_(2.5)generation,and the secondary transformation was enhanced as the increased PM_(2.5)concentrations.The results of WRF-CAMx showed obviously inter-transport of PM_(2.5)in the BTH region;the contribution of transportation source decreased significantly than previous reports in Beijing,Tianjin,and Baoding during the COVID-19 lockdown;but the contribution of industrial and residential emission sources increased significantly with the increase of PM_(2.5)concentration,and industry emission sources contributed the most to PM_(2.5)concentrations.Therefore,control policies should be devoted to reducing industrial emissions and regional joint control strategies to mitigate haze pollution.展开更多
Food hoarding is prevalent during the COVID-19 pandemic.To investigate the mechanism of urban consumers’food hoarding behaviors,we categorize hoarding motives into rational and irrational ones.Using random online sur...Food hoarding is prevalent during the COVID-19 pandemic.To investigate the mechanism of urban consumers’food hoarding behaviors,we categorize hoarding motives into rational and irrational ones.Using random online survey samples from three cities in China,we employ the multivariate probit model to investigate the rational and irrational motives on food hoarding behavior.Our results confirmed the existence of both rational and irrational food hoarding,and also found factors attributing to the different buying behaviors.The amount of food at hand and the expectation on the infection possibility of COVID-19 are two major factors affecting rational hoarding.Bad mood and herd psychology are factors contributing to panic buying.This study provides an empirical evidence to support intervention policies aiming at mitigating panic buying behavior.展开更多
The temporal variation of greenhouse gas concentrations in China during the COVID-19 lockdown in China is analyzed in this work using high resolution measurements of near surface ΔCO_(2),ΔCH_(4) andΔCO concentratio...The temporal variation of greenhouse gas concentrations in China during the COVID-19 lockdown in China is analyzed in this work using high resolution measurements of near surface ΔCO_(2),ΔCH_(4) andΔCO concentrations above the background conditions at Lin’an station(LAN),a regional background station in the Yangtze River Delta region.During the pre-lockdown observational period(IOP-1),bothΔCO_(2) andΔCH_(4) exhibited a significant increasing trend relative to the 2011-2019 climatological mean.The reduction ofΔCO_(2),ΔCH_(4) andΔCO during the lockdown observational period(IOP-2)(which also coincided with the Chinese New Year Holiday)reached up to 15.0 ppm,14.2 ppb and 146.8 ppb,respectively,and a reduction ofΔCO_(2)/ΔCO probably due to a dramatic reduction from industrial emissions.ΔCO_(2),ΔCH_(4) and ΔCO were observed to keep declining during the post-lockdown easing phase(IOP-3),which is the synthetic result of lower than normal CO_(2) emissions from rural regions around LAN coupled with strong uptake of the terrestrial ecosystem.Interestingly,the trend reversed to gradual increase for all species during the later easing phase(IOP-4),with ΔCO_(2)/ΔCO constantly increasing from IOP-2 to IOP-3 and finally IOP-4,consistent with recovery in industrial emissions associated with the staged resumption of economic activity.On average,ΔCO_(2) declined sharply throughout the days during IOP-2 but increased gradually throughout the days during IOP-4.The findings showcase the significant role of emission reduction in accounting for the dramatic changes in measured atmosphericΔCO_(2) and ΔCH_(4) associated with the COVID-19 lockdown and recovery.展开更多
Stringent quarantine measures during the Coronavirus Disease 2019(COVID-19)lockdown period(January 23,2020 to March 15,2020)have resulted in a distinct decrease in anthropogenic source emissions in North China Plain c...Stringent quarantine measures during the Coronavirus Disease 2019(COVID-19)lockdown period(January 23,2020 to March 15,2020)have resulted in a distinct decrease in anthropogenic source emissions in North China Plain compared to the paralleled period of 2019.Particularly,22.7%decrease in NO_(2)and 3.0%increase of O_(3)was observed in Tianjin,nonlinear relationship between O_(3)generation and NO_(2)implied that synergetic control of NOx and VOCs is needed.Deteriorating meteorological condition during the COVID-19 lockdown obscured the actual PM2.5 reduction.Fireworks transport in 2020 Spring Festival(SF)triggered regional haze pollution.PM2.5 during the COVID-19 lockdown only reduced by 5.6%in Tianjin.Here we used the dispersion coefficient to normalize the measured PM2.5(DN-PM2.5),aiming to eliminate the adverse meteorological impact and roughly estimate the actual PM2.5 reduction,which reduced by 17.7%during the COVID-19 lockdown.In terms of PM2.5 chemical composition,significant NO_(3)−increase was observed during the COVID-19 lockdown.However,as a tracer of atmospheric oxidation capacity,odd oxygen(Ox=NO_(2)+O_(3))was observed to reduce during the COVID-19 lockdown,whereas relative humidity(RH),specific humidity and aerosol liquid water content(ALWC)were observed with noticeable enhancement.Nitrogen oxidation rate(NOR)was observed to increase at higher specific humidity and ALWC,especially in the haze episode occurred during 2020SF,high air humidity and obvious nitrate generation was observed.Anomalously enhanced air humidity may response for the nitrate increase during the COVID-19 lockdown period.展开更多
In recent years,the police intervention strategy“Hot spots policing”has been effective in combating crimes.However,as cities are under the intense pressure of increasing crime and scarce police resources,police patr...In recent years,the police intervention strategy“Hot spots policing”has been effective in combating crimes.However,as cities are under the intense pressure of increasing crime and scarce police resources,police patrols are expected to target more accurately at finer geographic units rather than ballpark“hot spot”areas.This study aims to develop an algorithm using geographic information to detect crime patterns at street level,the so-called“hot street”,to further assist the Criminal Investigation Department(CID)in capturing crime change and transitive moments efficiently.The algorithm applies Kernel Density Estimation(KDE)technique onto street networks,rather than traditional areal units,in one case study borough in London;it then maps the detected crime“hot streets”by crime type.It was found that the algorithm could successfully generate“hot street”maps for Law Enforcement Agencies(LEAs),enabling more effective allocation of police patrolling;and bear enough resilience itself for the Strategic Crime Analysis(SCA)team’s sustainable utilization,by either updating the inputs with latest data or modifying the model parameters(i.e.the kernel function,and the range of spillover).Moreover,this study explores contextual characteristics of crime“hot streets”by applying various regression models,in recognition of the best fitted Geographically Weighted Regression(GWR)model,encompassing eight significant contextual factors with their varied effects on crimes at different streets.Having discussed the impact of lockdown on crime rates,it was apparent that the land-use driven mobility change during lockdown was a fundamental reason for changes in crime.Overall,these research findings have provided evidence and practical suggestions for crime prevention to local governors and policy practitioners,through more optimal urban planning(e.g.Low Traffic Neighborhoods),proactive policing(e.g.in the listed top 10“Hot Streets”of crime),publicizing of laws and regulations,and installations of security infrastructures(e.g.CCTV cameras and traffic signals).展开更多
The influence of reduction in emissions on the inherent temporal characteristics of PMand NOconcentration time series in six urban cities of India is assessed by computing the Hurst exponent using Detrended Fluctuatio...The influence of reduction in emissions on the inherent temporal characteristics of PMand NOconcentration time series in six urban cities of India is assessed by computing the Hurst exponent using Detrended Fluctuation Analysis(DFA) during the lockdown period(March 24–April 20, 2020) and the corresponding period during the previous two years(i.e., 2018 and 2019). The analysis suggests the anticipated impact of confinement on the PMand NOconcentration in urban cities, causing low concentrations. It is observed that the original PMand NOconcentration time series is persistent but filtering the time series by fitting the autoregressive process of order 1 on the actual time series and subtracting it changes the persistence property significantly. It indicates the presence of linear correlations in the PMand NOconcentrations. Hurst exponent of the PMand NOconcentration during the lockdown period and previous two years shows that the inherent temporal characteristics of the short-term air pollutant concentrations(APCs) time series do not change even after withholding the emissions. The meteorological variations also do not change over the three time periods. The finding helps in developing the prediction models for future policy decisions to improve urban air quality across cities.展开更多
Depending on various government policies,COVID-19(Corona Virus Disease-19) lockdowns have had diverse impacts on global aerosol concentrations.In 2022,Changchun a provincial capital city in Northeast China,suffered a ...Depending on various government policies,COVID-19(Corona Virus Disease-19) lockdowns have had diverse impacts on global aerosol concentrations.In 2022,Changchun a provincial capital city in Northeast China,suffered a severe COVID-19 outbreak and implemented a very strict lockdown that lasted for nearly two months.Using ground-based polarization Light Detection and Ranging(LiDAR),we detected real-time aerosol profile parameters(EC,extinction coefficient;DR,depolarization ratio;AOD,aerosol optical depth),as well as air-quality and meteorological indexes from 1 March to 30 April in 2021 and 2022 to quantify the effects of lockdown on aerosol concentrations.The period in 2022 was divided into three stages:pre-lockdown(1-10 March),strict lockdown(11 March to 10 April),and partial lockdown(11-30 April).The results showed that,during the strict lockdown period,compared with the pre-lockdown period,there were substantial reductions in aerosol parameters(EC and AOD),and this was consistent with the concentrations of the atmospheric pollutants PM_(2.5)(particulate matter with an aerodynamic diameter ≤2.5 μm) and PM_(2.5)(particulate matter with an aerodynamic diameter ≤10 μm),and the Oconcentration increased by 8.3%.During the strict lockdown,the values of EC within0-1 km and AOD decreased by 16.0% and 11.2%,respectively,as compared to the corresponding period in 2021.Lockdown reduced the conventional and organized emissions of air pollutants,and it clearly delayed the time of seasonal emissions from agricultural burning;however,it did not decrease the number of farmland fire points.Considering meteorological factors and eliminating the influence of wind-blown dust events,the results showed that reductions from conventional organized emission sources during the strict lockdown contributed to a 30% air-quality improvement and a 22% reduction in near-surface extinction(0-2 km).Aerosols produced by urban epidemic prevention and disinfection can also be identified using the EC.Regarding seasonal sources of agricultural straw burning,the concentrated burning induced by the epidemic led to the occurrence of heavy pollution from increased amounts of atmospheric aerosols,with a contribution rate of 62%.These results indicate that there is great potential to further improve air quality in the local area,and suggest that the comprehensive use of straw accompanied by reasonable planned burning is the best way to achieve this.展开更多
Athletes find innovative ways to stay in shape during COVID-19 lockdown The year 2020 was supposed to be a very busy one for sports in China.A number of major competitions were planned to be held throughout the year.T...Athletes find innovative ways to stay in shape during COVID-19 lockdown The year 2020 was supposed to be a very busy one for sports in China.A number of major competitions were planned to be held throughout the year.The Chinese Super League football season was due to start on February 22.展开更多
We present interesting application of artificial intelligence for investigating effect of the COVID-19 lockdown on 3-dimensional temperature variation across Nigeria(2°-15°E,4°-14°N),in equatorial ...We present interesting application of artificial intelligence for investigating effect of the COVID-19 lockdown on 3-dimensional temperature variation across Nigeria(2°-15°E,4°-14°N),in equatorial Africa.Artificial neural networks were trained to learn time-series temperature variation patterns using radio occultation measurements of atmospheric temperature from the Constellation Observing System for Meteorology,Ionosphere,and Climate(COSMIC).Data used for training,validation and testing of the neural networks covered period prior to the lockdown.There was also an investigation into the viability of solar activity indicator(represented by the sunspot number)as an input for the process.The results indicated that including the sunspot number as an input for the training did not improve the network prediction accuracy.The trained network was then used to predict values for the lockdown period.Since the network was trained using pre-lockdown dataset,predictions from the network are regarded as expected temperatures,should there have been no lockdown.By comparing with the actual COSMIC measurements during the lockdown period,effects of the lockdown on atmospheric temperatures were deduced.In overall,the mean altitudinal temperatures rose by about 1.1℃ above expected values during the lockdown.An altitudinal breakdown,at 1 km resolution,reveals that the values were typically below0.5℃ at most of the altitudes,but exceeded 1℃ at 28 and 29 km altitudes.The temperatures were also observed to drop below expected values at altitudes of 0-2 km,and 17-20 km.展开更多
Context and Objective: The nutritional and sports dimension of the lockdown implemented during the COVID-19 pandemic is unexplored in the African environment. The purpose of this study was to assess the effects of COV...Context and Objective: The nutritional and sports dimension of the lockdown implemented during the COVID-19 pandemic is unexplored in the African environment. The purpose of this study was to assess the effects of COVID-19 lockdown on body composition and fitness performance in Congolese football players. Methods: This was an observational study carried out in Brazzaville between February 9 and October 30, 2020. It included 16 male players among Congolese senior national team and 11 male football players of first division Brazzaville clubs. Two types of measurements were carried out: anthropometric measures (height, body mass, total fat percent, lean body mass);physical capacities [30 m sprint, repeated sprint, aerobic endurance (Yo-Yo Intermittent Recovery test), vertical jump (Squat Jump test, Countermovement test)]. The measurements were realized at 4 times: before lockdown (month of february, T0), 1<sup>st</sup> week of june (T1), 1<sup>st</sup> week of september (T2), 1<sup>st</sup> week of october (T3). Data were compared using Student t test, Sokal S test, Anova, Newman-Keuls test (multiple contrasts) and correlation analysis. Results: A significant increase in body mass (p Conclusion: The present data suggest that COVID-19 lockdown promotes weight gain and decreased physical ability in football players.展开更多
The massive lockdown of human socioeconomic activities and vehicle movements due to the COVID-19 pandemic in 2020 has resulted in an unprecedented reduction in pollutant gases such as Nitrogen Dioxide(NO_(2))and Carbo...The massive lockdown of human socioeconomic activities and vehicle movements due to the COVID-19 pandemic in 2020 has resulted in an unprecedented reduction in pollutant gases such as Nitrogen Dioxide(NO_(2))and Carbon Monoxide(CO)as well as Land Surface Temperature(LST)in Amman as well as all countries around the globe.In this study,the spatial and temporal variability/stability of NO_(2),CO,and LST throughout the lockdown period over Amman city have been analyzed.The NO_(2) and CO column density values were acquired from Sentinel-5p while the LST data were obtained from MODIS satellite during the lockdown period from 20 March to 24 April in 2019,2020,and 2021.The statistical analysis showed an overall reduction in NO_(2) in 2020 by around 27% and 48% compared to 2019 and 2021,respectively.However,an increase of 7% in 2021 compared to 2019 was observed because almost all anthropogenic activities were allowed during the daytime.The temporal persistence showed almost constant NO2 values in 2020 over the study area throughout the lockdown period.In addition,a slight decrease in CO(around 1%)was recorded in 2020 and 2021 compared to the same period in 2019.Restrictions on human activities resulted in an evident drop in LST in 2020 by around 13%and 18% less than the 5-year average and 2021 respectively.The study concludes that due to the restrictions imposed on industrial activities and automobile movements in Amman city,an unprecedented reduction in NO_(2),CO,and LST was recorded.展开更多
基金supported by the National Research Program for Key Issues in Air Pollution Control in China(No.DQGG202137)the National Natural Science Foundation of China(No.42277429)。
文摘The COVID-19 lockdown was a typical example of extreme emission reduction,providing an opportunity to study the impact of lockdown measures on air pollution.Particle number concentrations(PNC)originate from direct emissions or through new particle formation events.However,their variations during the lockdown period are under investigation.This study focuses on Luohe,a city on the southern edge of the North China Plain,analyzing the changes in PNC and its sources before,during,and after the COVID-19 lockdown.From March 25^(th)to May 31^(st),2022,real-time PNC measurements were conducted using a Scanning Mobility Particle Sizer for particle size.Results showed an 11.2%decrease in PNC during the lockdown compared to pre-lockdown and a 3.6%decrease compared to post-lockdown,indicating reduced local emissions and weakened regional transportation during the lockdown.Positive Matrix Factorization analysis identified six sources contributing to the total PNC,including photochemical nucleation,aged photochemical nucleation,gasoline vehicle emissions,diesel vehicle emissions,coal and biomass combustion,and secondary aerosols.The significant changes in source emissions indicate a substantially reduced traffic volume after the implementation of lockdown measures(2644.8#/cm^(3),2202.2#/cm^(3),2792.7#/cm^(3)).Concurrently,photochemical nucleation(310.1#/cm^(3),306.3#/cm^(3),393.1#/cm^(3))and photochemical nucleation aging(592.8#/cm^(3),744.1#/cm^(3),810.7#/cm^(3))exhibited increasing trends,while coal/biomass combustion(1656.6#/cm^(3),1586.2#/cm^(3),980.0#/cm^(3))and secondary sources(999.4#/cm^(3),791.1#/cm^(3),804.1#/cm^(3))showed decreasing trends.In summary,the contributions of traffic emissions to PNC highlight the potential for targeted traffic management strategies to improve urban air quality.
基金supported by the National Natural Science Foundation of China (Nos.22106129,22076174 and 91843301)。
文摘The outbreak of COVID-19 has caused concerns globally.To reduce the rapid transmission of the virus,strict city lockdown measures were conducted in different regions.China is the country that takes the earliest home-based quarantine for people.Although normal industrial and social activities were suspended,the spread of virus was efficiently controlled.Simultaneously,another merit of the city lockdown measure was noticed,which is the improvement of the air quality.Contamination levels of multiple atmospheric pollutants were decreased.However,in this work,24 and 14 air fine particulate matter(PM_(2.5))samples were continuously collected before and during COVID-19 city lockdown in Linfen(a typical heavy industrial city in China),and intriguingly,the unreduced concentration was found for environmentally persistent free radicals(EPFRs)in PM_(2.5)after normal life suspension.The primary non-stopped coal combustion source and secondary Cu-related atmospheric reaction may have impacts on this phenomenon.The cigarette-based assessment model also indicated possible exposure risks of PM_(2.5)-bound EPFRs during lockdown of Linfen.This study revealed not all the contaminants in the atmosphere had an apparent concentration decrease during city lockdown,suggesting the pollutants with complicated sources and formation mechanisms,like EPFRs in PM_(2.5),still should not be ignored.
基金the Tianjin Philosophy and Social Science Planning Project“Research on Value-Added Evaluation of Career Adaptability for Engineering Students Oriented towards Outstanding Engineers”,Grant Number TJJXQN22-001.
文摘Under the effects of COVID-19 and a number of ongoing lockdown tactics,anxiety symptoms and poor sleep quality have become common mental health issues among college freshmen and are intimately related to their emotional adaptation.To explore this connection,this study gathered data from a sample of 256 freshmen enrolled in an elite university in China in September 2022.The association between sleep quality,anxiety symptoms,and emotional adaptation was clarified using correlation analysis.Additionally,the mediating function of anxiety symptoms between sleep quality and emotional adaptation was investigated using a structural equation model.The results reveal that:(1)Chinese elite university freshmen who were subjected to prolonged lockdown had poor sleep quality and mild anxiety symptoms;(2)a significant positive correlation between poor sleep quality and anxiety symptoms was identified;(3)anxiety symptoms were found to have a significant negative impact on emotional adaptation;(4)poor sleep quality had a negative impact on emotional adaptation through anxiety symptoms.This research makes a valuable contribution by offering insights into the intricate relationship between sleep quality and emotional adaptation among freshmen in elite Chinese universities during prolonged lockdown conditions,and it is beneficial for schools and educators to further improve school schedules and psychological health initiatives.
文摘Introduction: The COVID-19 pandemic has affected all professional sectors to varying degrees. It has forced companies to restructure, initiate and promote telework. The aim was to study the impacts of COVID-19 lockdown on banking activities in Conakry. Materials and Methods: This was a descriptive cross-sectional study over seven months (from November 25, 2020 to June 27, 2021) and multicentric. It included thirteen of the eighteen banks of the main city of the capital Conakry (Kaloum). We analysed socio-demographic data and occupational characteristics. We paid particular attention to banking activities and medical datas. Results: During our study period, 875 workers met to our criteria, one third of whom were men. The average age was 37.93 ± 9.39 years [22 - 71]. Financial accounters were the most represented and average seniority at the job was 5.35 years. The work schedule was reduced during lockdown but an telework increased (29.8%). On the medical datas, the prevalence of COVID-19 was 20.7%;the lethality rate was 0.6% and the absentee rate 15.6%. The COVID-19 lockdown has deeply impacted the banking activities in Conakry particularly the productivity by a significant decrease in net banking income. Conclusion: Despite the continuity of activities during this pandemic, banks have experienced a reduction in their productivity resulting in a significant decrease in net banking income. These impacts of COVID-19 on the banking sector reflect its impact on the national economy.
文摘The potential hypotheses for finance research based on social media sentiment revolve around the reliability of investor sentiment expressed on social media and the causal relationship between financial markets and this sentiment.The central hypothesis we focus on is derived from the"lie game"played by investors on social media.This study is the first to explore three states of this lie game in the context of the Chinese stock market:the"equilibrium state",the"confusion state",and the"subversion state".Our findings indicate that the"equilibrium"state is the typical state of the lie game,where increased investor sentiment results in more positive market behavior,and higher stock prices lead to increased investor sentiment.We also examine the effect of significant social events,such as the"lockdown in Wuhan"and the"lockdown in Shanghai",on the lie game's outcome.The successful lockdown in Wuhan and the public's opposition to the politicization of COVID-19 reinforced the"equilibrium"state of the game.However,the Shanghai lockdown's failure to promptly halt the spread of COVID-19 led to the intertwining of the economy and COVID-19 in public discourse,shifting the lie game's outcome from an"equilibrium state"to a"subversive state".We emphasize that the"confusion state"and"subversion state"outcomes of the lie game are concerning,and managing public opinion and the externalization of domestic conflicts can help reduce this risk.This study offers a fresh perspective on the traditional issues of investor sentiment reliability and the causal relationship between investor sentiment and stock markets.
文摘The higher concentration of PM_(10) and PM_(2.5) in the lower atmosphere is severely harmful for human health and it also makes visibility diminution along with weather and climate modifications.The main objective is to find out the spatiotemporal variation and dispersal of PM_(10) and PM_(2.5) along with COVID-19 infection in the dusty city Kolkata.The consecutive two years PM_(10) and PM_(2.5) data of different stations have been obtained from State Pollution Control Board,Govt.of West Bengal.Forward trajectory analysis has been done through HYSPLIT(Hybrid Single Particle Lagrangian Integrated Trajectory)model to find the path and direction of air particles.The result showed that the various meteorological or environmental factors(such as temperature,relative humidity,wind,wind speed,pressure and gusty wind)and geographical location regulate the spatiotemporal variation of PM_(10) and PM_(2.5).These factors like high temperature with relative humidity and strong wind influence to disperse the particulate matters from north to south direction from city to outside during summer in Kolkata metropolitan city.During summer(both pre and lockdown years),the height of particles is extended up to 1000 m owing to active atmospheric ventilation whereas in winter it is confined within 100 m.The HYSPLIT model clearly specified that the particles dispersed from south,south-west to north and north east direction due to strong wind.The constant magnification of PM_(10) and PM_(2.5) in the lower atmosphere leads to greater frequency of COVID-19 infections and deaths.In Kolkata,the one of the crucial reasons of high infection and deaths(COVID-19)is co-morbidity of people.
基金supported by the National Natural Science Foundation of China (Nos.91644224,41805096)the National Key Research and Development Program of China (No.2016YFA0602003)+1 种基金the China Postdoctoral Science Foundation (No.2018M640169)the Natural Science Research Project for Universities of Jiangsu Province,China (No.18KJB170011)。
文摘To control the spread of COVID-19,rigorous restrictions have been implemented in China,resulting in a great reduction in pollutant emissions.In this study,we evaluated the air quality in the Yangtze River Delta during the COVID-19 lockdown period using satellite and ground-based data,including particle matter(PM),trace gases,water-soluble ions(WSIs) and black carbon(BC).We found that the impacts of lockdown policy on air quality cannot be accurately assessed using MODIS aerosol optical depth(AOD) data,whereas the tropospheric nitrogen dioxide(NO_(2)) vertical column density can well reflect the influences of these restrictions on human activities.Compared to the pre-COVID period,the PM_(2.5),PM_(10),NO_(2),carbon monoxide(CO),BC and WSIs during the lockdown in Suzhou were observed to decrease by 37.2%,38.3%,64.5%,26.1%,53.3% and 58.6%,respectively,while the sulfur dioxide(SO_(2)) and ozone(O_(3)) increased by 1.5% and 104.7%.The WSIs ranked in the order of NO_(3)~->NH_(4)^(+)>SO_(4)^(2-)>Cl~->Ca^(2+)>K^(+)>Mg^(2+)>Na + during the lockdown period.By comparisons with the ion concentrations during the pre-COVID period,we found that the ions NO 3-,NH 4 +,SO_(4)^(2-),Cl~-,Ca^(2+),K^(+) and Na^(+) decreased by 66.3%,48.8%,52.9%,56.9%,57.9% and 76.3%,respectively,during the lockdown,in contrast to Mg^(2+),which increased by 30.2%.The lockdown policy was found to have great impacts on the diurnal variations of Cl~-,SO_(4)^(2-),Na^(+) and Ca^(2+).
基金Financial support was received from the Universitat de València for the VLC-CAMPUS“Atraccióde Talent”PhD fellowship(awarded to C.B-S)the Fundación Universidad Católica de Valencia San Vicente Mártir through Grant 2019–231–003UCV(awarded toá.S-A)。
文摘The COVID-19 pandemic has escalated into one of the largest crises of the 21 st Century.The new SARS-CoV-2 coronavirus,responsible for COVID-19,has spread rapidly all around the world.The Spanish Government was forced to declare a nationwide lockdown in view of the rapidly spreading virus and high mortality rate in the nation.This study investigated the impact of short-term lockdown during the period from March 15th to April 12th 2020 on the atmospheric levels of CO,SO_(2),PM_(10),O_(3),and NO_(2)over 11 representative Spanish cities.The possible influence of several meteorological factors(temperature,precipitation,wind,sunlight hours,minimum and maximum pressure)on the pollutants'levels were also considered.The results obtained show that the 4-week lockdown had significant impact on reducing the atmospheric levels of NO_(2)in all cities except for the small city of Santander as well as CO,SO_(2),and PM_(10)in some cities,but resulted in increase of O_(3)level.
基金supported by the National Science Foundation of China(Grant.No.41521004)the Gansu Provincial Special Fund Project for Guiding Scientific and Technological Innovation and Development(Grant No.2019ZX-06)the Fundamental Research Funds for the Central Universit-ies(lzujbky-2021-kb12)。
文摘Estimating the impacts on PM_(2.5)pollution and CO_(2)emissions by human activities in different urban regions is important for developing efficient policies.In early 2020,China implemented a lockdown policy to contain the spread of COVID-19,resulting in a significant reduction of human activities.This event presents a convenient opportunity to study the impact of human activities in the transportation and industrial sectors on air pollution.Here,we investigate the variations in air quality attributed to the COVID-19 lockdown policy in the megacities of China by combining in-situ environmental and meteorological datasets,the Suomi-NPP/VIIRS and the CO_(2)emissions from the Carbon Monitor project.Our study shows that PM_(2.5)concentrations in the spring of 2020 decreased by 41.87%in the Yangtze River Delta(YRD)and 43.30%in the Pearl River Delta(PRD),respectively,owing to the significant shutdown of traffic and manufacturing industries.However,PM_(2.5)concentrations in the Beijing-Tianjin-Hebei(BTH)region only decreased by 2.01%because the energy and steel industries were not fully paused.In addition,unfavorable weather conditions contributed to further increases in the PM_(2.5)concentration.Furthermore,CO_(2)concentrations were not significantly affected in China during the short-term emission reduction,despite a 19.52%reduction in CO_(2)emissions compared to the same period in 2019.Our results suggest that concerted efforts from different emission sectors and effective long-term emission reduction strategies are necessary to control air pollution and CO_(2)emissions.
基金supported by the National Key R&D Program of China(Nos.2019YFC0214800 and 2018YFC0213203)the Fundamental Research Funds for Central Public Welfare Scientific Research Institutes of China,Chinese Research Academy of Environmental Sciences(No.2019YSKY-012)
文摘To investigate the characteristics of particulate matter with an aerodynamic diameter less than 2.5μm(PM_(2.5))and its chemical compositions in the Beijing-Tianjin-Hebei(BTH)region of China during the novel coronavirus disease(COVID-19)lockdown,the ground-based data of PM_(2.5),trace gases,water-soluble inorganic ions,and organic and elemental carbon were analyzed in three typical cities(Beijing,Tianjin,and Baoding)in the BTH region of China from 5-15 February 2020.The PM_(2.5)source apportionment was established by combining the weather research and forecasting model and comprehensive air quality model with extensions(WRF-CAMx).The results showed that the maximum daily PM_(2.5)concentration reached the heavy pollution level(>150μg/m^(3))in the above three cities.The sum concentration of SO_(4)^(2-),NO_(3)^(-)and NH_(4)^(+)played a dominant position in PM_(2.5)chemical compositions of Beijing,Tianjin,and Baoding;secondary transformation of gaseous pollutants contributed significantly to PM_(2.5)generation,and the secondary transformation was enhanced as the increased PM_(2.5)concentrations.The results of WRF-CAMx showed obviously inter-transport of PM_(2.5)in the BTH region;the contribution of transportation source decreased significantly than previous reports in Beijing,Tianjin,and Baoding during the COVID-19 lockdown;but the contribution of industrial and residential emission sources increased significantly with the increase of PM_(2.5)concentration,and industry emission sources contributed the most to PM_(2.5)concentrations.Therefore,control policies should be devoted to reducing industrial emissions and regional joint control strategies to mitigate haze pollution.
基金The authors thank the National Natural Science Foundation of China(72003008)the Social Science Funding from Beijing Municipal Education Commission,China(SM201810011002)2017 Beijing High Level Group Building Program,China(IDHT20170505).
文摘Food hoarding is prevalent during the COVID-19 pandemic.To investigate the mechanism of urban consumers’food hoarding behaviors,we categorize hoarding motives into rational and irrational ones.Using random online survey samples from three cities in China,we employ the multivariate probit model to investigate the rational and irrational motives on food hoarding behavior.Our results confirmed the existence of both rational and irrational food hoarding,and also found factors attributing to the different buying behaviors.The amount of food at hand and the expectation on the infection possibility of COVID-19 are two major factors affecting rational hoarding.Bad mood and herd psychology are factors contributing to panic buying.This study provides an empirical evidence to support intervention policies aiming at mitigating panic buying behavior.
基金supported by the National Nature Science Foundation of China(Nos.41730103,41805129)
文摘The temporal variation of greenhouse gas concentrations in China during the COVID-19 lockdown in China is analyzed in this work using high resolution measurements of near surface ΔCO_(2),ΔCH_(4) andΔCO concentrations above the background conditions at Lin’an station(LAN),a regional background station in the Yangtze River Delta region.During the pre-lockdown observational period(IOP-1),bothΔCO_(2) andΔCH_(4) exhibited a significant increasing trend relative to the 2011-2019 climatological mean.The reduction ofΔCO_(2),ΔCH_(4) andΔCO during the lockdown observational period(IOP-2)(which also coincided with the Chinese New Year Holiday)reached up to 15.0 ppm,14.2 ppb and 146.8 ppb,respectively,and a reduction ofΔCO_(2)/ΔCO probably due to a dramatic reduction from industrial emissions.ΔCO_(2),ΔCH_(4) and ΔCO were observed to keep declining during the post-lockdown easing phase(IOP-3),which is the synthetic result of lower than normal CO_(2) emissions from rural regions around LAN coupled with strong uptake of the terrestrial ecosystem.Interestingly,the trend reversed to gradual increase for all species during the later easing phase(IOP-4),with ΔCO_(2)/ΔCO constantly increasing from IOP-2 to IOP-3 and finally IOP-4,consistent with recovery in industrial emissions associated with the staged resumption of economic activity.On average,ΔCO_(2) declined sharply throughout the days during IOP-2 but increased gradually throughout the days during IOP-4.The findings showcase the significant role of emission reduction in accounting for the dramatic changes in measured atmosphericΔCO_(2) and ΔCH_(4) associated with the COVID-19 lockdown and recovery.
基金supported by the Tianjin Natural Science Foundation(No.18JCYBJC23100)the Tianjin Science and Technology Foundation(No.18ZXSZSF00160)+1 种基金the National Natural Science Foundation of China(No.41771242)the China Postdoctoral Science Foundation(No.2019M660984).
文摘Stringent quarantine measures during the Coronavirus Disease 2019(COVID-19)lockdown period(January 23,2020 to March 15,2020)have resulted in a distinct decrease in anthropogenic source emissions in North China Plain compared to the paralleled period of 2019.Particularly,22.7%decrease in NO_(2)and 3.0%increase of O_(3)was observed in Tianjin,nonlinear relationship between O_(3)generation and NO_(2)implied that synergetic control of NOx and VOCs is needed.Deteriorating meteorological condition during the COVID-19 lockdown obscured the actual PM2.5 reduction.Fireworks transport in 2020 Spring Festival(SF)triggered regional haze pollution.PM2.5 during the COVID-19 lockdown only reduced by 5.6%in Tianjin.Here we used the dispersion coefficient to normalize the measured PM2.5(DN-PM2.5),aiming to eliminate the adverse meteorological impact and roughly estimate the actual PM2.5 reduction,which reduced by 17.7%during the COVID-19 lockdown.In terms of PM2.5 chemical composition,significant NO_(3)−increase was observed during the COVID-19 lockdown.However,as a tracer of atmospheric oxidation capacity,odd oxygen(Ox=NO_(2)+O_(3))was observed to reduce during the COVID-19 lockdown,whereas relative humidity(RH),specific humidity and aerosol liquid water content(ALWC)were observed with noticeable enhancement.Nitrogen oxidation rate(NOR)was observed to increase at higher specific humidity and ALWC,especially in the haze episode occurred during 2020SF,high air humidity and obvious nitrate generation was observed.Anomalously enhanced air humidity may response for the nitrate increase during the COVID-19 lockdown period.
基金partly supported by King’s Global Engagement Partnership Fund[2020-2021#PF2021_Mar_005].
文摘In recent years,the police intervention strategy“Hot spots policing”has been effective in combating crimes.However,as cities are under the intense pressure of increasing crime and scarce police resources,police patrols are expected to target more accurately at finer geographic units rather than ballpark“hot spot”areas.This study aims to develop an algorithm using geographic information to detect crime patterns at street level,the so-called“hot street”,to further assist the Criminal Investigation Department(CID)in capturing crime change and transitive moments efficiently.The algorithm applies Kernel Density Estimation(KDE)technique onto street networks,rather than traditional areal units,in one case study borough in London;it then maps the detected crime“hot streets”by crime type.It was found that the algorithm could successfully generate“hot street”maps for Law Enforcement Agencies(LEAs),enabling more effective allocation of police patrolling;and bear enough resilience itself for the Strategic Crime Analysis(SCA)team’s sustainable utilization,by either updating the inputs with latest data or modifying the model parameters(i.e.the kernel function,and the range of spillover).Moreover,this study explores contextual characteristics of crime“hot streets”by applying various regression models,in recognition of the best fitted Geographically Weighted Regression(GWR)model,encompassing eight significant contextual factors with their varied effects on crimes at different streets.Having discussed the impact of lockdown on crime rates,it was apparent that the land-use driven mobility change during lockdown was a fundamental reason for changes in crime.Overall,these research findings have provided evidence and practical suggestions for crime prevention to local governors and policy practitioners,through more optimal urban planning(e.g.Low Traffic Neighborhoods),proactive policing(e.g.in the listed top 10“Hot Streets”of crime),publicizing of laws and regulations,and installations of security infrastructures(e.g.CCTV cameras and traffic signals).
文摘The influence of reduction in emissions on the inherent temporal characteristics of PMand NOconcentration time series in six urban cities of India is assessed by computing the Hurst exponent using Detrended Fluctuation Analysis(DFA) during the lockdown period(March 24–April 20, 2020) and the corresponding period during the previous two years(i.e., 2018 and 2019). The analysis suggests the anticipated impact of confinement on the PMand NOconcentration in urban cities, causing low concentrations. It is observed that the original PMand NOconcentration time series is persistent but filtering the time series by fitting the autoregressive process of order 1 on the actual time series and subtracting it changes the persistence property significantly. It indicates the presence of linear correlations in the PMand NOconcentrations. Hurst exponent of the PMand NOconcentration during the lockdown period and previous two years shows that the inherent temporal characteristics of the short-term air pollutant concentrations(APCs) time series do not change even after withholding the emissions. The meteorological variations also do not change over the three time periods. The finding helps in developing the prediction models for future policy decisions to improve urban air quality across cities.
基金the Key Research Program of Frontier Sciences,Chinese Academy of Sciences (No. QYZDB-SSW-DQC045)the National Natural Science Foundation of China (No. 41775116)。
文摘Depending on various government policies,COVID-19(Corona Virus Disease-19) lockdowns have had diverse impacts on global aerosol concentrations.In 2022,Changchun a provincial capital city in Northeast China,suffered a severe COVID-19 outbreak and implemented a very strict lockdown that lasted for nearly two months.Using ground-based polarization Light Detection and Ranging(LiDAR),we detected real-time aerosol profile parameters(EC,extinction coefficient;DR,depolarization ratio;AOD,aerosol optical depth),as well as air-quality and meteorological indexes from 1 March to 30 April in 2021 and 2022 to quantify the effects of lockdown on aerosol concentrations.The period in 2022 was divided into three stages:pre-lockdown(1-10 March),strict lockdown(11 March to 10 April),and partial lockdown(11-30 April).The results showed that,during the strict lockdown period,compared with the pre-lockdown period,there were substantial reductions in aerosol parameters(EC and AOD),and this was consistent with the concentrations of the atmospheric pollutants PM_(2.5)(particulate matter with an aerodynamic diameter ≤2.5 μm) and PM_(2.5)(particulate matter with an aerodynamic diameter ≤10 μm),and the Oconcentration increased by 8.3%.During the strict lockdown,the values of EC within0-1 km and AOD decreased by 16.0% and 11.2%,respectively,as compared to the corresponding period in 2021.Lockdown reduced the conventional and organized emissions of air pollutants,and it clearly delayed the time of seasonal emissions from agricultural burning;however,it did not decrease the number of farmland fire points.Considering meteorological factors and eliminating the influence of wind-blown dust events,the results showed that reductions from conventional organized emission sources during the strict lockdown contributed to a 30% air-quality improvement and a 22% reduction in near-surface extinction(0-2 km).Aerosols produced by urban epidemic prevention and disinfection can also be identified using the EC.Regarding seasonal sources of agricultural straw burning,the concentrated burning induced by the epidemic led to the occurrence of heavy pollution from increased amounts of atmospheric aerosols,with a contribution rate of 62%.These results indicate that there is great potential to further improve air quality in the local area,and suggest that the comprehensive use of straw accompanied by reasonable planned burning is the best way to achieve this.
文摘Athletes find innovative ways to stay in shape during COVID-19 lockdown The year 2020 was supposed to be a very busy one for sports in China.A number of major competitions were planned to be held throughout the year.The Chinese Super League football season was due to start on February 22.
文摘We present interesting application of artificial intelligence for investigating effect of the COVID-19 lockdown on 3-dimensional temperature variation across Nigeria(2°-15°E,4°-14°N),in equatorial Africa.Artificial neural networks were trained to learn time-series temperature variation patterns using radio occultation measurements of atmospheric temperature from the Constellation Observing System for Meteorology,Ionosphere,and Climate(COSMIC).Data used for training,validation and testing of the neural networks covered period prior to the lockdown.There was also an investigation into the viability of solar activity indicator(represented by the sunspot number)as an input for the process.The results indicated that including the sunspot number as an input for the training did not improve the network prediction accuracy.The trained network was then used to predict values for the lockdown period.Since the network was trained using pre-lockdown dataset,predictions from the network are regarded as expected temperatures,should there have been no lockdown.By comparing with the actual COSMIC measurements during the lockdown period,effects of the lockdown on atmospheric temperatures were deduced.In overall,the mean altitudinal temperatures rose by about 1.1℃ above expected values during the lockdown.An altitudinal breakdown,at 1 km resolution,reveals that the values were typically below0.5℃ at most of the altitudes,but exceeded 1℃ at 28 and 29 km altitudes.The temperatures were also observed to drop below expected values at altitudes of 0-2 km,and 17-20 km.
文摘Context and Objective: The nutritional and sports dimension of the lockdown implemented during the COVID-19 pandemic is unexplored in the African environment. The purpose of this study was to assess the effects of COVID-19 lockdown on body composition and fitness performance in Congolese football players. Methods: This was an observational study carried out in Brazzaville between February 9 and October 30, 2020. It included 16 male players among Congolese senior national team and 11 male football players of first division Brazzaville clubs. Two types of measurements were carried out: anthropometric measures (height, body mass, total fat percent, lean body mass);physical capacities [30 m sprint, repeated sprint, aerobic endurance (Yo-Yo Intermittent Recovery test), vertical jump (Squat Jump test, Countermovement test)]. The measurements were realized at 4 times: before lockdown (month of february, T0), 1<sup>st</sup> week of june (T1), 1<sup>st</sup> week of september (T2), 1<sup>st</sup> week of october (T3). Data were compared using Student t test, Sokal S test, Anova, Newman-Keuls test (multiple contrasts) and correlation analysis. Results: A significant increase in body mass (p Conclusion: The present data suggest that COVID-19 lockdown promotes weight gain and decreased physical ability in football players.
文摘The massive lockdown of human socioeconomic activities and vehicle movements due to the COVID-19 pandemic in 2020 has resulted in an unprecedented reduction in pollutant gases such as Nitrogen Dioxide(NO_(2))and Carbon Monoxide(CO)as well as Land Surface Temperature(LST)in Amman as well as all countries around the globe.In this study,the spatial and temporal variability/stability of NO_(2),CO,and LST throughout the lockdown period over Amman city have been analyzed.The NO_(2) and CO column density values were acquired from Sentinel-5p while the LST data were obtained from MODIS satellite during the lockdown period from 20 March to 24 April in 2019,2020,and 2021.The statistical analysis showed an overall reduction in NO_(2) in 2020 by around 27% and 48% compared to 2019 and 2021,respectively.However,an increase of 7% in 2021 compared to 2019 was observed because almost all anthropogenic activities were allowed during the daytime.The temporal persistence showed almost constant NO2 values in 2020 over the study area throughout the lockdown period.In addition,a slight decrease in CO(around 1%)was recorded in 2020 and 2021 compared to the same period in 2019.Restrictions on human activities resulted in an evident drop in LST in 2020 by around 13%and 18% less than the 5-year average and 2021 respectively.The study concludes that due to the restrictions imposed on industrial activities and automobile movements in Amman city,an unprecedented reduction in NO_(2),CO,and LST was recorded.
