Advancing automated pupillometry:a practical deep learning model utilizing infrared pupil images

AIM:To establish pupil diameter measurement algorithms based on infrared images that can be used in real-world clinical settings.METHODS:A total of 188 patients from outpatient clinic at He Eye Specialist Shenyang Hospital from Spetember to December 2022 were included,and 13470 infrared pupil images were collected for the study.All infrared images for pupil segmentation were labeled using the Labelme software.The computation of pupil diameter is divided into four steps:image pre-processing,pupil identification and localization,pupil segmentation,and diameter calculation.Two major models are used in the computation process:the modified YoloV3 and Deeplabv 3+models,which must be trained beforehand.RESULTS:The test dataset included 1348 infrared pupil images.On the test dataset,the modified YoloV3 model had a detection rate of 99.98% and an average precision(AP)of 0.80 for pupils.The DeeplabV3+model achieved a background intersection over union(IOU)of 99.23%,a pupil IOU of 93.81%,and a mean IOU of 96.52%.The pupil diameters in the test dataset ranged from 20 to 56 pixels,with a mean of 36.06±6.85 pixels.The absolute error in pupil diameters between predicted and actual values ranged from 0 to 7 pixels,with a mean absolute error(MAE)of 1.06±0.96 pixels.CONCLUSION:This study successfully demonstrates a robust infrared image-based pupil diameter measurement algorithm,proven to be highly accurate and reliable for clinical application.

Robust Facial Biometric Authentication System Using Pupillary Light Reflex for Liveness Detection of Facial Images

Pupil dynamics are the important characteristics of face spoofing detection.The face recognition system is one of the most used biometrics for authenticating individual identity.The main threats to the facial recognition system are different types of presentation attacks like print attacks,3D mask attacks,replay attacks,etc.The proposed model uses pupil characteristics for liveness detection during the authentication process.The pupillary light reflex is an involuntary reaction controlling the pupil’s diameter at different light intensities.The proposed framework consists of two-phase methodologies.In the first phase,the pupil’s diameter is calculated by applying stimulus(light)in one eye of the subject and calculating the constriction of the pupil size on both eyes in different video frames.The above measurement is converted into feature space using Kohn and Clynes model-defined parameters.The Support Vector Machine is used to classify legitimate subjects when the diameter change is normal(or when the eye is alive)or illegitimate subjects when there is no change or abnormal oscillations of pupil behavior due to the presence of printed photograph,video,or 3D mask of the subject in front of the camera.In the second phase,we perform the facial recognition process.Scale-invariant feature transform(SIFT)is used to find the features from the facial images,with each feature having a size of a 128-dimensional vector.These features are scale,rotation,and orientation invariant and are used for recognizing facial images.The brute force matching algorithm is used for matching features of two different images.The threshold value we considered is 0.08 for good matches.To analyze the performance of the framework,we tested our model in two Face antispoofing datasets named Replay attack datasets and CASIA-SURF datasets,which were used because they contain the videos of the subjects in each sample having three modalities(RGB,IR,Depth).The CASIA-SURF datasets showed an 89.9%Equal Error Rate,while the Replay Attack datasets showed a 92.1%Equal Error Rate.

Observation of Low-Level Jets in the Eastern Tropical Indian Ocean Based on Shipborne Coherent Doppler Lidar

In contrast to the Pacific and Atlantic Oceans,the Indian Ocean has lacked in-situ observations of wind profiles over open sea areas for decades.In 2021,a shipborne coherent Doppler lidar(CDL)was used to observe in-situ wind profiles in the eastern tropical Indian Ocean.This equipment successfully captured low-level jets(LLJs)in the region,and their characteristics were thoroughly analyzed.Results reveal that the observed wind speed of LLJs in the eastern Indian Ocean ranges from 6 m s^(-1) to 10 m s^(-1) during the boreal winter and spring seasons,showing a height range of 0.6 to 1 km and two peak times at 0800 and 2000 UTC.This wind shear is weaker than that in land or offshore areas,ranging from 0 s^(-1) to 0.006 s^(-1).Moreover,the accuracy of the CDL data is compared to that of ERA5 data in the study area.The results indicate that the zonal wind from ERA5 data significantly deviated from the CDL measurement data,and the overall ERA5 data are substantially weaker than the in-situ observations.Notably,ERA5 underestimates northwestward LLJs.

Eating Patterns and Daily Dietary Recall of Primary School Pupils: An Empirical Evidence from A School Feeding Scheme

The objective of this study was to experimentally evaluate children’s daily food memory and eating habits.The study found that the gender and school location had an impact on the nutritional condition of primary school students as well as the school food scheme.The investigations were based on three hypotheses and three research questions.In this study,the Eating Habits and Daily Dietary Recall Scale was the tool utilized to gather data(EPDDRS).Four experts—three from the department of vocational education and one lecturer in test and measurement evaluation—validated the instrument’s face.The dependability indices of EPDDRS were calculated using Cronbach’s Alpha.While delivering the instruments,the researcher used the direct administration and retrieval approach.58 instructors and a sample size of 1240 students were selected using a systematic random selection approach.The obtained data was examined using mean and standard deviation to address the research objectives,and the null hypotheses were tested using t-test statistics and Analysis of variance(ANOVA)at the 0.05 level of significance.The main conclusions of this study were that the school meal program had a favorable impact on the students’nutritional status.Also,a balanced ration of nutrient-dense meals that were suitably varied was supplied for the students via the school food program.Also,the findings revealed a substantial difference in the mean assessments of male and female students about their eating patterns.On the school meal program’s dietary recall list,students from high,middle,and low socioeconomic status differ significantly.Recommendations were given to the government,schools,and parents based on the study’s findings.The study’s shortcomings were discussed,and recommendations for more research were made.

Pupils in Wenchuan Earthquake

A great earthquake broke out in WenChuan. A lot of people were killed, but somany people were rescused by soldiers.Here are stories about three recused pupils.Langzhen, aged three, was rescusedby the soldiers after being buried in ruinsfor 10 hours.

THE INVESTIGATION AND ANALYSIS OF THE PSYCHOLOGICAL DISORDERS OF THE PUPILS（9～12YEARS OF AGE）OF XI＇AN CITY

pupils aged 9～12 years from six primary schools were cross-sectionally investigated on the psychological disorders with Conner Scale and EPQ. The results showed that the incidence of psychological disorders was 18. 2%,with 21. 3% in male and 15. 5% in female. The incidehees were significantly difrerent between male and remal (P<0. 05). The incidences or learning difficulty,hyperactivity and impulsive behavior were 8. 2%, 5. 3%,and 5.3% respectively.The family factors influencing the psychological disorders were the pupils'birth problems,the relationship between the pupils and their parents, and the parents'inappropriate prospect for the pupils.The investigation also found that the pupils with psychological disorders had more poor experiences or their family and school and more of them had obvious personality tendencies towards unstability or emotion,eccentricity and social immaturity as compared with the normal pupils. The effective measures to promote pupils'psychological health were suggested in this article.

The Roles of Low-level Jets in “21·7” Henan Extremely Persistent Heavy Rainfall Event

An extremely heavy rainfall event lasting from 17 to 22 July 2021 occurred in Henan Province of China, with accumulated precipitation of more than 1000 mm over a 6-day period that exceeded its mean annual precipitation. The present study examines the roles of persistent low-level jets(LLJs) in maintaining the precipitation using surface station observations and reanalysis datasets. The LLJs triggered strong ascending motions and carried moisture mainly from the outflow of Typhoon In-fa(2021). The varying directions of the LLJs well corresponded to the meridional shifts of the rainfall. The precipitation rate reached a maximum during 20-21 July as the LLJs strengthened and expanded vertically into double LLJs, including synoptic-weather-system-related LLJs(SLLJs) at 850–700 hPa and boundary-layer jets(BLJs)at ~950 hPa. The coupling of the SLLJ and BLJ provided strong mid-and low-level convergence on 20 July, whereas the SLLJ produced mid-level divergence at its entrance that coupled with low-level convergence at the terminus of the BLJ on21 July. The formation mechanisms of the two types of LLJs are further examined. The SLLJs and the low-pressure vortex(or inverted trough) varied synchronously as a whole and were affected by the southwestward movement of the WPSH in the rainiest period. The persistent large total pressure gradient force at low levels also maintained the strength of low-level geostrophic winds, thus sustaining the BLJs on the synoptic scale. The results based on a Du-Rotunno 1D model show that the Blackadar and Holton mechanisms jointly governed the BLJ dynamics on the diurnal scale.

Research on the prevalence of conduct disorders among primary school pupils in Khartoum-Sudan

The aim of this research was to investigate conduct disorder among pupils of primary schools in Khartoum, the capital of Sudan. School survey descriptive method was used and 384 pupils were selected from primary schools through systematic sampling technique. Age ranged from 5 to 17 years old with a mean of (9.34) years. The tools of data collection consisted of the Sutter-Eyberg Student Behavior Inventory. The statis-tical tests used to analyze the collected data involve frequency and percentage, Pearson co-efficient of correlation, mean, t-test for one sample and t-test for two independent samples. The results of this research revealed that that the prevalence of conduct disorder among pupils of primary schools in Khartoum was low. There were significant differences in conduct disorder between male and females pupils. There were no significant differences between pupils of pre-paratory classes and pupils of elementary classes. There was no significant correlation between conduct disorder and age.

Food Behavior of Pupils in the City of Bobo-Dioulasso (Burkina Faso)

Introduction: Diet is a determinant of chronic non transmissible diseases. The aim of this study was to describe pupils’ diet in the city of Bobo-Dioulasso (Burkina Faso). Methods: This was a descriptive cross-sectional study that took place from March to April 2016, among 1st, 4th and 7th form pupils of public and private schools in the city of Bobo-Dioulasso. Diet survey methods were a reminder of the last 24 hours and the questionnaire of consumption frequency. Results: A total of 1993 pupils were surveyed. The mean age was 17.5 ± 3.6 years and the sex ratio 0.7. The majority of pupils (90.5%) reported eating at least 3 meals a day. Dietary recommendations were different according to food groups. For example, vegetables (90.0%), fruits (75.4%) and dairy products (79.3%) were the least well consumed foods compared to recommendations. Protein and starch intake were inadequate among these pupils with 39.7% and 58.2% respectively. Almost 1/4 had a regular weekly alcohol consumption (23.4%) while an excessive consumption of sweet drinks and fried foods was noted in 12.7% and 28.2% of them, respectively. Conclusion: This study has revealed a general insufficiency in the recommended dietary intakes of fruit, vegetables, proteins, starchy foods and dairy products among pupils, and on the other hand, a regular consumption of fatty, sugary and alcoholic foods for about a fifth of them. An intervention program such as “Communication for Continuous Behavior Change” would help improve these habits.

A Study of Anthropometric Indices among Pupils in Rural Communities around Kainji Dam, Niger State

The physical and mental development of pupils could be arrested by inadequate food intake and infection with immediate and long term consequences. This has implications on decreased school performances, lower intelligent quotient levels, poor psychosocial development, and decreased cognitive functions. This study assessed the growth and body fat distribution among pupils aged 5 - 19 years. A cross-sectional study was conducted among pupils from five primary schools in different communities around Kainji Dam. This assessment was based on a comparison with reference standards set by the World Health Organization to determine their deviations. A qualified registered nurse carried out physical measurements to obtain age, height, and body weight using electronic weighing scale and stadiometer. Data were analyzed using Anthroplusv1.0.4 software. The overall prevalence of stunting was 21.5% with 8% being severely stunted. The prevalence of thinness was 35.2% with 11.2% being wasted while the overall prevalence of underweight was not calculated for children > 10 years old. The prevalence of underweight for 5 - 10 years old children was 16.9% with 2.4% being severely underweight. The curves for both male and female children deviated from normal distribution. Females have higher percentage of stunting than males. This study revealed a high prevalence of thinness and stunting which is the consequence of poor nutrition arising from multifaceted and interrelated circumstances such as poor feeding, eating practices and repeated infection. Intervention such as Home Grown School Feeding Programme of the Government is a right step in improving the nutritional status of pupils in rural communities.

Effect of socio-demographic status on dental caries in pupils by using a multilevel hurdle model

Introduction: Dental caries is the most prevalent chronic disease among schoolchildren. We aimed to investigate the association between dental caries index and socio-demographic status in schoolchildren by using a multilevel hurdle model. Materials and Methods: A cross-sectional epidemiological study was carried out on 906 primary school pupils in Kerman, Iran in 2012. The subjects were selected through a stratified cluster random sampling. At first, the whole target area was stratified according to two geographic areas, the north and south area. Then each area was stratified according to gender. In the next step, several schools were considered as clusters, which were selected randomly in each geographic area and gender strata. All the schoolchildren in these schools were included in this study as samples. Twelve-year-old pupils were examined for dental caries. The dependent variable in this study was the dmft/DMFT index. Eight variables, including socio-demographic information, were collected. Multilevel negative binomial hurdle model was employed for data analysis. Results: The prevalence of caries-free pupils was 30.1% and the mean dmft/DMFT was 3.6 ± 2.2. Negative binomial part of the adjusted model showed that the dmft/DMFT adjusted rate for females was 1.36 (95% CI: 1.10-1.79) times higher than males. Also, the dmft/DMFT adjusted rate for overweight pupils was 0.86 (95% CI: 0.74-0.98) times lower than those with normal weight. Logistic part of the adjusted model showed that the posibility of caries-free state in overweight pupils was 1.95 (95% CI: 1.22-3.11) times higher than those with normal weight. In addition, pupils whose fathers and mothers were workers and housewives, respectively, and those with a high maternal age were at a greater risk for caries experience than others (p < 0.05). Conclusion: BMI, gender, parent’s job and mother’s age at delivery were factors effecting on dental caries in schoolchildren. These pupils need more attention to dental care.

Too Sweet/Too Fatty Food Consumption: Determinants among Secondary School Pupils in the City of Bobo-Dioulasso (Burkina Faso)

Introduction: Nutrition, particularly when too sweet or too fatty, is a major determinant of chronic diseases. This study aims to determine the frequency and associate factors of the excessive consumption of sweet drinks and fried food among secondary school pupils. Methods: It is cross-sectional study which was conducted from March to April 2016 among 1st, 4th and 7th form pupils of public and private schools in the city of Bobo-Dioulasso. Nutritional investigation methods consisted in a reminder of the last 24 hours associated with a questionnaire on food consumption frequency. Excessive consumption of sweet drinks was defined as a consumption of more than 3 sweet drinks (soda) or sugary juice per day (~33 cl × 3);and excessive consumption of fried food as a consumption of more than 1 intake of fried food per day. Results: In total, 1993 pupils were interviewed. The mean age was 17.5 ± 3.6 years and sex-ratio 0.7. Excessive consumption of sweet drinks and fried food was recorded in 12.7% (n = 253) and 28.2% (n = 561) of pupils, respectively. The factors associated with excessive consumption of sweet drinks were: sex/female, sedentarily, desire to gain weight, lean or normal corpulence of the mother and breakfast intake;those associated with excessive consumption of fried food were: sex/female, being in 1st or 4th form, physical exercise practice and breakfast intake. But the fact to attend a private secondary school, to have a mother of normal corpulence and a concordance between self-image and actual weight status, were protective against excessive consumption of fried foods. Conclusion: This study has displayed prominently the fact that eating too sweet and too fatty concerned respectively 1/10 and 3/10 of pupils in the city of Bobo-Dioulasso. The main modifiable factors of these eating habits included the level of education, the composition of breakfast and the influence of mothers. An intervention program in the form of a Communication for Continuous Behavioral Change intended for pupils and their mothers could help to improve this situation.

A novel method for gamma spectrum analysis of low-level and intermediate-level radioactive waste

The uncertainty of nuclide libraries in the analysis of the gamma spectra of low-and intermediate-level radioactive waste(LILW)using existing methods produces unstable results.To address this problem,a novel spectral analysis method is proposed in this study.In this method,overlapping peaks are located using a continuous wavelet transform.An improved quadratic convolution method is proposed to calculate the widths of the peaks and establish a fourth-order filter model to estimate the Compton edge baseline with the overlapping peaks.Combined with the adaptive sensitive nonlinear iterative peak,this method can effectively subtracts the background.Finally,a function describing the peak shape as a filter is used to deconvolve the energy spectrum to achieve accurate qualitative and quantitative analyses of the nuclide without the aid of a nuclide library.Gamma spectrum acquisition experiments for standard point sources of Cs-137 and Eu-152,a segmented gamma scanning experiment for a 200 L standard drum,and a Monte Carlo simulation experiment for triple overlapping peaks using the closest energy of three typical LILW nuclides(Sb-125,Sb-124,and Cs-134)are conducted.The results of the experiments indicate that(1)the novel method and gamma vision(GV)with an accurate nuclide library have the same spectral analysis capability,and the peak area calculation error is less than 4%;(2)compared with the GV,the analysis results of the novel method are more stable;(3)the novel method can be applied to the activity measurement of LILW,and the error of the activity reconstruction at the equivalent radius is 2.4%;and(4)The proposed novel method can quantitatively analyze all nuclides in LILW without a nuclide library.This novel method can improve the accuracy and precision of LILW measurements,provide key technical support for the reasonable disposal of LILW,and ensure the safety of humans and the environment.

Asymptomatic Carriage of Salmonella and Intestinal Parasites in Pupils in Yaounde

Background: Feco-oral transmitted diseases (FOTD) remain a public health issue, particularly in developing countries. Data concerning the carriage of Salmonella and intestinal parasites in children are available worldwide but are lacking in Cameroon. This study aimed to determine the asymptomatic carriage of Salmonella and intestinal parasites in children of two primary schools in Yaoundé. Methods: A cross-sectional descriptive study was conducted from October 2017 to May 2018 in two primary schools (from rural and urban areas) in the 7th precinct of Yaoundé. Sociodemographic, clinical and paraclinical (rectal swab, direct examination of fresh stool and bacteriological culture on Hektoen medium) data were collected. Results: We included 368 (192 boys) pupils from both schools (184 in each school) with a mean age of 8.99 ± 2.21 years. None of the children was infected by Salmonella spp. Intestinal parasite prevalence was 9.80% (6.52% of children from the urban school vs 13.04% from the rural ones). The intestinal parasite prevalence tended to be higher in girls than in boys (11.98% vs. 7.39%). Among intestinal parasites, protozoa were the most widely found. Entamoeba histolytica and Giardia intestinalis were the most prevalent pathogenic intestinal protozoa (11.11% vs. 25% of all positive stool exams). The helminths, less frequent, were represented by Ascaris lumbicoides and Enterobius vermicularis. The factors associated with intestinal parasite carriage were mainly rural school location and age between 11 - 13 years. Conclusion: Among children in primary school, Salmonella infection was absent, while intestinal parasites are frequent, represented mostly by protozoa. This parasitism is in our cohort associated with the rural school location and the 11 - 13 years age group. This suggests that there is additional room for the implementation of prevention measures for intestinal parasite infections in our setting.

The Human Eye Pupil Detection System Using BAT Optimized Deep Learning Architecture

The pupil recognition method is helpful in many real-time systems,including ophthalmology testing devices,wheelchair assistance,and so on.The pupil detection system is a very difficult process in a wide range of datasets due to problems caused by varying pupil size,occlusion of eyelids,and eyelashes.Deep Convolutional Neural Networks(DCNN)are being used in pupil recognition systems and have shown promising results in terms of accuracy.To improve accuracy and cope with larger datasets,this research work proposes BOC(BAT Optimized CNN)-IrisNet,which consists of optimizing input weights and hidden layers of DCNN using the evolutionary BAT algorithm to efficiently find the human eye pupil region.The proposed method is based on very deep architecture and many tricks from recently developed popular CNNs.Experiment results show that the BOC-IrisNet proposal can efficiently model iris microstructures and provides a stable discriminating iris representation that is lightweight,easy to implement,and of cutting-edge accuracy.Finally,the region-based black box method for determining pupil center coordinates was introduced.The proposed architecture was tested using various IRIS databases,including the CASIA(Chinese academy of the scientific research institute of automation)Iris V4 dataset,which has 99.5%sensitivity and 99.75%accuracy,and the IIT(Indian Institute of Technology)Delhi dataset,which has 99.35%specificity and MMU(Multimedia University)99.45%accuracy,which is higher than the existing architectures.

Axial length shortening in myopic children with Stickler syndrome after repeated low-level red-light therapy

AIM:To report the myopia-controlling effect of repeated low-level red-light(RLRL)therapy in patients with Stickler syndrome(STL),an inherited collagenic disease typically presenting with early onset myopia.METHODS:Three STL children,aged 3,7,and 11y,received RLRL therapy throughout the follow-up period of 17,3,and 6mo,respectively after exclusion of fundus anomalies.Data on best-corrected visual acuity(BCVA),intraocular pressure,cycloplegic subjective refraction,ocular biometrics,scanning laser ophthalmoscope,optical coherence tomography,genetic testing,systemic disease history,and family history were recorded.RESULTS:At the initiation of the RLRL therapy,the spherical equivalent(SE)of 6 eyes from 3 patients ranged from-3.75 to-20.38 D,axial length(AL)were from 23.88 to 30.68 mm,and BCVA were from 0.4 to 1.0(decimal notation).Myopia progression of all six eyes slowed down after RLRL therapy.AL in five out of the six eyes shortened-0.07 to-0.63 mm.No side effects were observed.CONCLUSION:Three cases of STL whose progression of myopic shift and AL elongation are successfully reduced and even reversed after RLRL therapy.

The Level of General Physical Performance and Physical Development of 10-Year-Old Pupils

This contribution deals with the level of general physical performance of 10-year-old male and female pupils attending primary schools. Fourth grade pupils attending primary schools in Banska Bystrica were tested in the number of 433 pupils （220 boys and 213 girls）. The following indicators of general physical performance were monitored： sit-and-reach, standing long jump, sit-ups, flexed arm hang, shuttle run 4 ×10 m, endurance shuttle run. Also basic somatic indicators such as body height, body weight and BM! were found out. 10-year-old boys achieve better level in five tests of general physical performance. The girls achieve statistically better level in one test. When comparing it with the previous researches in Slovakia, we noted a lower level of general physical performance but a higher level of indicators of physical development of boys and girls from Banska Bystrica. Used set of tests affects the whole range of general physical performance, and it is adequate to the temporal, spatial and material conditions of schools.

The Influence of Parent-Child Relationship on Pupils’ Learning Motivation: The Mediating Role of Teacher-Student Relationship

Objective:The study is to analyze the influence of parent-child relationship on pupils’learning motivation,and to explore the mediating mechanism of teacher-student relationship in parent-child relationship and learning motivation.Method:This study conducted a questionnaire survey on 213 pupils in Grades 5 and 6 in two schools in Beijing using Pianta’s teacher-student relationship scale revised by Qu,Dornbush’s parent-child intimacy scale revised by Zhang and the learning motivation scale adapted by Hu.Results:Gender,grade,whether they are the only child and to be a class cadre or not show significant differences in some dimensions of parent-child relationship,teacher-student relationship and learning motivation.The total scores of parent-child relationship,teacher-student relationship and learning motivation are positively correlated,and some sub dimensions are also significantly correlated.Parent-child relationship and teacher-student relationship have a significant positive predictive effect on learning motivation,and parent-child relationship has a significant positive predictive effect on teacher-student relationship.Teacher-student relationship plays a mediating role in the influence of parent-child relationship on learning motivation.Conclusions:Parent-child relationship can promote the relationship between teachers and students,and then enhance pupils’learning motivation.

Formation of Low-Level Jets over Southern China in the Mei-yu Season

This study examines the diversity of low-level jet(LLJ)formation and related physical processes over southern China.A total of 171 LLJ formation events with enhanced daily southwesterlies and early-morning maximum wind speeds were observed during the mei-yu seasons of 1989–2018.The LLJs can be further categorized into four types based on the increases in the daily mean and diurnal amplitude of the low-level winds.Analysis of the synoptic-scale disturbances shows that the two types of LLJ formation(Q1 and Q4),which feature large increases of daily southerly wind components,are mainly induced by west-east dipole patterns of pressure change,in association with the enhanced southwest vortex and/or the western Pacific subtropical high(WPSH).In contrast,the other two types(Q2 and Q3),which feature relatively large increases in their daily westerly components,are related to a northwest-southeast dipole pattern of pressure change due to the mid-latitude trough and the WPSH.We further analyze the considerable variations in the diurnal thermal forcing among the LLJ formation events.The strong(weak)daytime heating of solar radiation leads to relatively large(small)increases in the diurnal amplitude of low-level winds in Q1 and Q2(Q3 and Q4)types.Therefore,different combinations of synopticscale disturbances and diurnal thermal forcings are found to account for the diversity in LLJ formation and associated differences in downstream rainfall patterns.These results help to improve our understanding and prediction of the formation of LLJs.

Thermodynamics and Microphysical Characteristics of an Extreme Rainfall Event Under the Influence of a Low-level Jet over the South China Coast

In this paper,the data of Automatic Weather Stations(AWSs),ERA5 reanalysis,sounding,wind profile radar,and dual-polarization radar are used to study an extreme rainfall event in the south China Coast on 11 to 12 May 2022 from the aspects of thermodynamics and microphysical characteristics under the influence of low-level jets(LLJs).Results show that:(1)The extreme rainfall event can be divided into two stages:the first stage(S1)from 0000 to 0600 LST on May 12 and the second stage(S2)from 0700 to 1700 LST on the same day.During S1,the rainfall is mainly caused by the upper-level shortwave trough and the boundary layer jet(BLJ),characterized by strong upward motion on the windward side of mountains.In S2,the combined influence of the BLJ and synoptic-system-related low-level jet(SLLJ)increases the vertical wind shear and vertical vorticity,strengthening the rainstorm.In combination with the effect of topography,a warm and humid southwest flow continuously transports water vapor to farther north,resulting in a significant increase in rainfall over the study area(on the terrain’s windward slope).From S1 to S2,the altitude of a divergence center in the upper air decreases obviously.(2)The rainfalls in the two stages are both associated with the mesoscale convergence line(MCL)on the surface,and the wind field from the mesoscale outflow boundary(MOB)in S1 is in the same direction as the environmental winds.Due to a small area of convergence that is left behind the MOB,convection moves eastward quickly and causes a short duration of heavy rainfall.In S2,the convergence along the MOB is enhanced,which strengthens the rainfall and leads to strong outflows,further enhancing the surface convergence near the MOB and forming a positive feedback mechanism.It results in a slow motion of convection and a long duration of heavy rainfall.(3)In terms of microphysics,the center of a strong echo in S1 is higher than in S2.The warm-rain process of the oceanic type characterizes both stages,but the convective intensity in S2 is significantly stronger than that in S1,featuring bigger drop sizes and lower concentrations.It is mainly due to the strengthening of LLJs,which makes small cloud droplets lift to melting levels,enhancing the ice phase process(riming process),producing large amounts of graupel particles and enhancing the melting and collision processes as they fall,resulting in the increase of liquid water content(LWC)and the formation of large raindrops near the surface.