Measurement and analysis of the resilience characteristics for a regional agricultural soil-water resource composite system.

Resilience is a significant attribute used to measure the sustainable development of the environment, and research on optimal measurement models is very important. This study took 15 farms in the Jiansanjiang Administration of Heilongjiang Province in China as the research object and constructed a resilience evaluation indicator system containing 31 indicators for the regional agricultural soil-water resource composite system (ASWRS). The combined weight (BFCM-CRITIC) and entropy weight (EW) combined with the variable fuzzy assessment (VFA) model and the improved technique for order preference by similarity to an ideal solution (TOPSIS) model were used to calculate the resilience exponent and to analyse the characteristics of space-time variation. The stability and reliability of the two models under different weights were verified by the Spearman correlation coefficient and discrimination theory to determine the optimal resilience exponent diagnosis method. The results show that according to the BFCM-CRITIC-VFA model, the levels of resilience were the highest at the Nongjiang, Hongwei and Erdaohe farms, and the resilience levels were strong and scattered. The resilience of the Jiansanjiang Administration has been increasing over time, and the spatial distribution has generally decreased from north to south and from the Heilong River and Wusuli River basins inland. A comparison of the reliability and stability of the two models for different weights indicates that the VFA model optimized based on combined weights was superior to the other methods in terms of stability and reliability, which verifies that the BFCM-CRITIC-VFA model is the most suitable for measuring the resilience exponent.

The temporal distribution of platinum group elements (PGEs) in PM2.5.

In this paper, Changji, Xinjiang, northwest China, was selected as the study area, and platinum group elements (PGEs) in PM2.5 were quantified by ICP-MS using microwave digestion. The results indicated that the average concentrations (and range) of Rh, Pd, and Pt in PM2.5 were 0.21 (n.d. -1.41) ng/m3, 8.09 (n.d. -59.50) ng/m3, and 0.12 (n.d. -0.83) ng/m3, respectively. The concentration of Pd was significantly higher than Rh and Pt. Moreover, the seasonal variations of Rh and Pd were the same: highest in summer and lower in other seasons. However, the seasonal variation of Pt was opposite to that of Rh and Pd: highest in winter and lower in other seasons. Seasonal differences in emission sources of PGEs and the climatic characteristics of arid regions played important roles in the seasonal changes of PGEs. Rh and Pd had a common source and similar diurnal variation. The major influencing factors were traffic volume and meteorological conditions. The diurnal variation regularity of Pt was different from Rh and Pd. The superimposed effect of vehicle exhaust emissions and coal-fired emissions was the main reason why the diurnal variation of Pt was more complicated than those of Rh and Pd. The diurnal concentration of Pt varied with the seasons. It is caused by seasonal coal combustion and meteorological conditions.

Changes in microbial communities at different soil depths through the first rainy season following severe wildfire in North China artificial Pinus tabulaeformis forest.

Wildfire could result in dramatic changes to soil temperatures and environments, with immediate, short- or long-lasting impacts on soil microbes. However, relatively little research has documented how fire disturbance, soil depth, time variation and their interactions affect soil microbial communities in wet conditions. This study investigated a severe wildfire influenced on bacterial and fungal communities at four soil depths (0-5, 5-10, 10-15 and 15-20 cm) after two quarters (with similar precipitation and exactly during the rainy season). Soil sampling was conducted in a burned site relative to an undisturbed contiguous site in the North China artificial Pinus tabulaeformis forest. Results indicated that fire had significant effects on bacterial and fungal richness, diversity, composition and structure, including most impacts on the surface mineral soil (0-5 cm) within the first period post-fire and minor impacts on the subsoils (5-20 cm) up to the second period. The microbial richness and some dominant taxa in the undisturbed soils changed with time and depth, suggesting spatiotemporal variation in soil microbial communities although the effects of rainfall were weakened. These differences in microbes between burned and undisturbed soils were mainly driven by soil pH, whereas organic matter and available potassium mediated the distribution of microbial communities along depth and time, respectively. In addition, fungal community was more sensitive to fire and time than bacterial community but an opposite result was found in depth. Nevertheless, soil microbes showed some signs of adaptation to fire. This work advocate that non-intervention should be considered in the short term after a fire or low-intensity water replenishment in the case of aridity.

Temporal Trends in the Risk Factors and Clinical Characteristics of Ischemic Stroke in Young Adults.

OBJECTIVES: This study aimed to analyze the risk factors of ischemic stroke in young adults of different ages; explore the changes in these risk factors with time; analyze the clinical characteristics of ischemic stroke in young adults; and assess how to better prevent ischemic stroke in young adults. METHODS: All patients with ischemic stroke who presented to the Department of Emergency Medicine, Nanjing Drum Tower Hospital, Affiliated Hospital of Nanjing University Medical School were enrolled. The data of patients aged 18-50 years were retrospectively evaluated for two periods, January-December 2008 and January-December 2018. Additionally, we collected the data of patients aged 51-90 years with ischemic stroke in the same ward in 2018. The subjects were divided into three groups: ischemic stroke in young people in 2008 ("Youth 2008"), ischemic stroke in young people in 2018 ("Youth 2018"), and ischemic stroke in elderly people in 2018 ("Senior 2018"). Risk factors, clinical characteristics and test indices were recorded and analyzed statistically. RESULTS: The "Youth 2008" group included 28 patients-19 males (67.9%) and 9 females (31.2%) with a male-to-female ratio of 2.11:1. The "Youth 2018" group included 23 patients-20 males (87.0%) and 3 females (13.0%) with a male-to-female ratio of 6.67:1. The "Senior 2018" group included 210 patients-150 males (71.4%) and 60 females (28.6%) with a male-to-female ratio of 2.50:1. The risk factors in "Youth 2018" were higher than those in "Youth 2008" in terms of hypertension, hyperglycemia, and hypercholesterolemia without significant difference. Smoking and hypertrophic cardiomyopathy were significantly increased (P < 0.05) in this population. Smoking, hypercholesterolemia, and hypertrophic cardiomyopathy were more prevalent among the "Youth 2018" group than among the "Senior 2018" group, whereas carotid plaques, hypertension, and atrial fibrillation were less common in the younger group (P < 0.05). There was no significant difference between the younger and older groups in terms of thrombolysis rate, cerebral infarction type, and complications, except pulmonary infections (P < 0.05). CONCLUSIONS: There was no significant change in the main risk factors of ischemic stroke in young adults during the 10-year period. Traditional risk factors-smoking and hypertrophic cardiomyopathy-were still common but with a significantly greater prevalence, whereas carotid plaques, hypertension, and atrial fibrillation had become less common. The clinical characteristics, other than pulmonary infection, were not significantly different between the younger and older patients with ischemic stroke.

First Eigenmode Transmission by High Efficient CSI Estimation for Multiuser Massive MIMO Using Millimeter Wave Bands.

Drastic improvements in transmission rate and system capacity are required towards 5th generation mobile communications (5G). One promising approach, utilizing the millimeter wave band for its rich spectrum resources, suffers area coverage shortfalls due to its large propagation loss. Fortunately, massive multiple-input multiple-output (MIMO) can offset this shortfall as well as offer high order spatial multiplexing gain. Multiuser MIMO is also effective in further enhancing system capacity by multiplexing spatially de-correlated users. However, the transmission performance of multiuser MIMO is strongly degraded by channel time variation, which causes inter-user interference since null steering must be performed at the transmitter. This paper first addresses the effectiveness of multiuser massive MIMO transmission that exploits the first eigenmode for each user. In Line-of-Sight (LoS) dominant channel environments, the first eigenmode is chiefly formed by the LoS component, which is highly correlated with user movement. Therefore, the first eigenmode provided by a large antenna array can improve the robustness against the channel time variation. In addition, we propose a simplified beamforming scheme based on high efficient channel state information (CSI) estimation that extracts the LoS component. We also show that this approximate beamforming can achieve throughput performance comparable to that of the rigorous first eigenmode transmission. Our proposed multiuser massive MIMO scheme can open the door for practical millimeter wave communication with enhanced system capacity.

Lap time variation and executive function in older adults: the Baltimore Longitudinal Study of Aging.

BACKGROUND: poor cognitive and motor performance predicts neurological dysfunction. Variable performance may be a subclinical indicator of emerging neurological problems. OBJECTIVE: examine the cross-sectional association between a clinically accessible measure of variable walking and executive function. METHODS: older adults aged 60 or older from the Baltimore Longitudinal Study of Aging (n = 811) with data on the 400-m walk test and cognition. Based on ten 40-m laps, we calculated mean lap time (MLT) and variation in time across ten 40-m laps (lap time variation, LTV). Executive function tests assessed attention and short-term memory (digit span forward and backward), psychomotor speed [Trail Making Test (TMT) part A] and multicomponent tasks requiring cognitive flexibility [TMT part B, part B-A (Delta TMT) and digit symbol substitution test (DSST)]. Multivariate linear regression analysis examined the cross-sectional association between LTV and executive function, adjusted for MLT, age, sex and education, as well as the LTV × MLT interaction. RESULTS: the LTV was univariately associated with all executive function tests except digit span (P < 0.001); after adjustment, the association with TMT part A remained (standardised ß = 0.142, P = 0.002). There was an interaction between MLT and LTV; among fast walkers, greater LTV was associated with a greater Delta TMT (ß for LTV × MLT = -1.121, P = 0.016) after adjustment. CONCLUSION: at any walking speed, greater LTV is associated with psychomotor slowing. Among persons with faster walking speed, variation is associated with worse performance on a complex measure of cognitive flexibility. A simple measure of variability in walking time is independently associated with psychomotor slowing.

Towards uniform accelerometry analysis: a standardization methodology to minimize measurement bias due to systematic accelerometer wear-time variation.

Accelerometers are predominantly used to objectively measure the entire range of activity intensities - sedentary behaviour (SED), light physical activity (LPA) and moderate to vigorous physical activity (MVPA). However, studies consistently report results without accounting for systematic accelerometer wear-time variation (within and between participants), jeopardizing the validity of these results. This study describes the development of a standardization methodology to understand and minimize measurement bias due to wear-time variation. Accelerometry is generally conducted over seven consecutive days, with participants' data being commonly considered 'valid' only if wear-time is at least 10 hours/day. However, even within 'valid' data, there could be systematic wear-time variation. To explore this variation, accelerometer data of Smart Cities, Healthy Kids study (www.smartcitieshealthykids.com) were analyzed descriptively and with repeated measures multivariate analysis of variance (MANOVA). Subsequently, a standardization method was developed, where case-specific observed wear-time is controlled to an analyst specified time period. Next, case-specific accelerometer data are interpolated to this controlled wear-time to produce standardized variables. To understand discrepancies owing to wear-time variation, all analyses were conducted pre- and post-standardization. Descriptive analyses revealed systematic wear-time variation, both between and within participants. Pre- and post-standardized descriptive analyses of SED, LPA and MVPA revealed a persistent and often significant trend of wear-time's influence on activity. SED was consistently higher on weekdays before standardization; however, this trend was reversed post-standardization. Even though MVPA was significantly higher on weekdays both pre- and post-standardization, the magnitude of this difference decreased post-standardization. Multivariable analyses with standardized SED, LPA and MVPA as outcome variables yielded more stable results with narrower confidence intervals and smaller standard errors. Standardization of accelerometer data is effective in not only minimizing measurement bias due to systematic wear-time variation, but also to provide a uniform platform to compare results within and between populations and studies. Key pointsSystematic variation in accelerometer wear-time both, within and between participants results in measurement bias.Standardization of data after controlling for wear-time produces stable outcome variables.Descriptive and multivariate analyses conducted with standardized outcome variables minimize measurement bias.

Time variation of high-risk groups for liver function deteriorations within fluctuating long-term liver function after hepatic radiotherapy in patients with hepatocellular carcinoma.

PURPOSE: The purpose of this study is to find essential risk factors associated with liver function (LF) deteriorations within fluctuating long-term LF and their time-varying effects in patients with hepatocellular carcinoma (HCC) receiving hepatic radiotherapy and to identify high-risk groups for adverse LF deteriorations and their changes over time in facilitating the prevention of hepatic decompensation and the improvement of survival. MATERIALS AND METHODS: A total of 133 HCC patients treated by hepatic radiotherapy were enrolled. A study design was conducted to convert posttreatment long-term LF with fluctuating levels over time to recurrent LF events using defined upgrades in a grading scale. The hazard ratios (HR) of pretreatment biochemical, demographic, clinical, and dosimetric factors in developing posttreatment LF events were estimated using the Cox model. Methodologies of the counting process approach, robust variance estimation, goodness-of-fit testing based on the Schoenfeld residuals, and time-dependent covariates in survival analysis were employed to handle the correlation within subjects and evaluate the time-varying effects during long-term follow-up. RESULTS: Baseline LF score before radiotherapy and gender were significant factors. Initial HR in developing LF events was 1.17 (95% CI 1.11-1.23; P < 0.001) for each increase of baseline LF score and kept almost constant over time (HR, 1.00; 95% CI 1.00-1.01; P = 0.065). However, no difference was observed regarding initial hazards for gender (HR, 1.00; 95% CI 0.64-1.56; P = 0.994), but the hazard for women got higher monthly over time compared with men (HR, 1.04; 95% CI 1.01-1.07; P = 0.006). CONCLUSIONS: High-risk groups for adverse LF deteriorations after hepatic radiotherapy may change over time. Patients with poor baseline LF are vulnerable from the beginning. Women require prevention strategies and careful monitoring for deteriorations at a later stage.

Spatiotemporal variability characteristics of extreme climate events in Xinjiang during 1960-2019.

Under the global warming, it is particularly important to explore the response of extreme climate to global climate change over the arid regions. Based on daily temperature (maximum, minimum, and average) and precipitation data from meteorological stations in Xinjiang, China, we analyzed the spatiotemporal characteristics of extreme temperature and extreme precipitation events via combining thin plate smoothing spline function interpolation, Sen's slope, and Mann-Kendall test. Our results showed that during 1960-2019, the extreme low temperature index of frost days (FD), icing days (ID), cold days (TX10p), cold nights (TN10p), and cold speel duration index (CSDI) all showed the downward trend to varying degrees, and the extreme high temperature index of summer days (SD25), warm days (TX90p), warm night (TN90p), and warm speel duration index (WSDI) all showed an upward trend to varying degrees, and the extreme low temperature index of high altitude mountains decreases more than that of the basin and plains. In addition, all the extreme temperature indices are closely related to the annual average temperature in Xinjiang (R > 0.6). Among the extreme precipitation indices, except for the consecutive dry days (CDD), the other extreme precipitation indices showed increasing trends to different degrees, but the changes in extreme precipitation in Xinjiang were mainly manifested by the increase of heavy precipitation in a short period (the increase of heavy precipitation and extreme heavy precipitation was the largest, 44.8 mm/10a and 17.6 mm/10a, respectively) and spatially concentrated in the Ili River and Altai Mountains in northern Xinjiang. Meanwhile, annual precipitation was positively correlated with the extreme precipitation index (R > 0.4), except for the CDD. This study provides theoretical support for the prevention and control of natural disasters in the dry zone.

Working time variation and mental health during the Covid-19 pandemic in China.

The Covid-19 pandemic has brought about a significant shift in labor market dynamics, leading to a notable increase in labor market flexibilization. One prominent aspect of this transformation is the growing variation in working time patterns. The irregular and unpredictable nature of working time may contribute to increased stress levels, difficulty in establishing routines, and challenges in maintaining work-life boundaries. Drawing on China General Social survey 2021, this study aims to examine (1) the relationship between working time variation and mental health during the Covid-19 pandemic in China; (2) whether the relationship can be mediated by work-family conflict; (3) to what extent the relationship varies across occupations. We find that working time variation is associated with significantly worse mental health during the Covid-19 pandemic in China, and around half of the negative effect can be mediated by increased work-family conflict. Moreover, the negative association is more pronounced among non-professional occupations than professional occupations. Overall, these findings shed light on the detrimental impact of working time variation on mental health and its potential mechanism, highlighting how novel work paradigm may interact with existing labor market inequalities to shape workers' mental health.

[Characteristics of Atmospheric Dust Fall Pollution and Its Chemical Composition and Mass Reconstruction in Mentougou District of Beijing].

To study the characteristics of atmospheric dust fall pollution in Mentougou District of Beijing, the monthly average monitoring results of 57 atmospheric dust fall samples from two state-controlled ambient air stations in Mentougou District from 2018 to 2022 were collected, and the atmospheric dust fall pollution status and its time variation characteristics in Mentougou District were analyzed. In order to explore the characteristics of chemical components of atmospheric dust fall and the results of quality mass reconstruction and their sources, 57 dust fall samples were collected using the active suction method at the Sanjiadian State-controlled Ambient Air Station. The mass concentration of dust fall and its chemical components were measured, the characteristics of chemical components in atmospheric dust fall were studied, and the mass reconstruction of the main components of atmospheric dust fall was performed using particle mass reconstruction technology. The reliability of the mass reconstruction results and the reasons for its undetermined components were also discussed. The results showed that from 2018 to 2022, the monthly dust fall in Mentougou District of Beijing changed periodically, being the maximum in April or May in spring and the minimum in October or November in autumn, and the maximum monthly dust fall was 3.2 to 8.4 times the minimum monthly dust fall. The order of the quarterly average monthly dust fall was as follows:spring>summer>autumn>winter, and the dust fall mainly came from spring and summer, accounting for 40.1%-43.0% and 23.8%-37.5% of the total annual dust fall, respectively. The annual average monthly dust fall in Mentougou District of Beijing showed a significant downward trend. The dust fall in 2022 had decreased by 52.8% compared with that in 2018, with an average annual decline of 13.2%, which was related to the improvement in the fine management level of urban environmental protection in Beijing in recent years. In 2021, soil dust had a significant impact on dust fall in Mentougou District, with an actual contribution of 44.2%. The chemical components in the atmospheric dust fall in Mentougou District were mainly water-soluble ions, crustal elements, organic carbon(OC), and elemental carbon(EC). The total mass of the measured chemical components accounted for 65.0% of the mass fraction of the dust fall. The secondary organic carbon(SOC) was also an important component of the atmospheric dust fall, and its mass concentration was 13.5 µg·m-3, accounting for 96.4% of the mass fraction of OC. The main components of atmospheric dust fall mass reconstruction were crust element fugitive dust, organic matter(OM), SO42-, NO3-, NH4+, trace elements, EC, and Cl-, with mass concentrations of 34.8, 28.0, 20.6, 15.0, 5.6, 4.3, 3.2, and 2.2 µg·m-3, accounting for 25.5%, 20.6%, 15.1%, 11.1%, 4.1%, 3.2%, 2.3%, and 1.6% of the dust fall quality, respectively. The atmospheric dust fall mainly came from the soil dust, construction cement dust, biomass combustion, waste incineration, and secondary transformation process. The measured mass concentration of atmospheric dust fall had a good correlation with the reconstructed mass concentration of chemical components, and the determination coefficient R2 was 0.8173. The undetermined components in the mass reconstruction results accounted for 16.5% of the dust fall mass, of which the particle bound water(PBW) in the dust fall accounted for 6.2% of the dust fall mass, and the remaining undetermined components might have been related to the unmeasured components, the selected estimation coefficient of OM and crustal elemental dust, the particle size composition, the selected chemical component analysis method, and its measurement error.

Analysis of road traffic injuries presented to the emergency department in the Eastern Province of Saudi Arabia: a hospital-based study.

The increasing incidence of road traffic injuries (RTIs) has contributed to the disability and death of millions of people on both a national and global level. This retrospective study was conducted at King Fahad University Hospital (KFUH), Khobar, Saudi Arabia, and included all patients who presented at the emergency department due to road traffic accidents (RTAs) between January 1st, 2022, and December 31st, 2022. Patient data was retrieved from the health information system at KFUH. Descriptive and inferential analysis were performed with several variables analyzed using multivariate logistic regression and factorial ANOVA (MANOVA). During this period, 921 patients were treated at the hospital's emergency department. Of these, 611 (66.3%) were men and 310 (33.7%) were women. The most frequently affected age group was 16-25, representing 427 (46.4%) cases. Most patients were Saudi citizens (837, 90.9%). Among the patients, 19 (2.1%) required surgical treatment within 24 hours of the RTA, and 29 (3.1%) were admitted to the surgical intensive care unit (SICU). There were eight fatalities, representing 0.9% of the cases. January had the highest number of RTAs (12.7%). Moreover, 463 individuals (50.3%) had some form of injury, the most common type being lacerations and abrasions (n=228, 24.8%). Upper limb fractures were the most frequent type of fracture, occurring in 73 cases (7.9%). Being male (P=0.001), non-Saudi (P=0.014), and experiencing accidents during June and July (P=0.002) were associated with an increased prevalence of injury. Mortality had a statistically significant relationship with different patient age groups (P=0.014), patient citizenship (P=0.005), and length of hospital stay (P<0.001).

[Characteristics and Health Risk Assessment of BTESX in the Northern Suburbs of Nanjing].

AMA GC5000BTX was used to monitor the mixing ratio of benzene, toluene, ethylbenzene, m,p-xylene, o-xylene, and styrene (BTESX) in the atmosphere of the northern suburb of Nanjing from January 2014 to December 2016. The temporal variation characteristics of BTESX and the influence of meteorological elements on it were analyzed, and the characteristic ratio method (T/B) was used to qualitatively analyze the source of BTESX. Finally, the human exposure analysis and evaluation method of EPA was used to evaluate the health risk of BTESX. The results showed that during the observation period, the average mixing ratio of BTESX was (7.28±6.63)×10-9, and the mixing ratio of benzene was the highest at (2.45±3.91)×10-9. The mixing ratio of other species from large to small was toluene>ethylbenzene>m,p-xylene>o-xylene>styrene, which were (2.41±2.61)×10-9, (1.37±1.28)×10-9, (0.51±0.48)×10-9, (0.3±0.36)×10-9, and (0.22±0.42)×10-9, respectively. Due to the existence of stable aromatic sources, the monthly and seasonal variation in BTESX mixing ratio was not as obvious as that of other species (NOx, CO, SO2, PM2.5, etc.). The weekend effect of BTESX and other pollutants was not significant. The mixing ratio of BTESX was largely affected by the short distance transportation of chemical enterprises and traffic trunk roads in the northeast, resulting in a large mixing ratio of BTESX in the northeast. The mixing ratio of BTESX was jointly affected by relative humidity and temperature, and its high value area was mainly located in the range of 30%-70% relative humidity. In this range of relative humidity, the high value range of BTESX volume fraction increased with the elevation of temperature. The HI (hazard index) of BTESX in different seasons was within the safety range recognized by EPA, whereas the R (carcinogenic risk of benzene) value was higher than the safety threshold specified by EPA. At the same time, the HI and R values were higher in summer, to which great attention should be paid.

Analysis of time-space variations during dynamic cervical spine motion in cervical spondylosis myelopathy patients.

BACKGROUND CONTEXT: Decreased cervical range of motion (ROM) is a common symptom of myelopathy patients. Many previous studies have relied on a variety of experimental approaches for quantifying static cervical range of motion. However, the change rules of time-space variation during dynamic cervical spine motion remains unknown. PURPOSE: To develop and validate the effectiveness of a novel wearable robot-based sensor system, Analysis of Dynamic Cervical spine Motion (ADCM), in evaluating the dynamic cervical spine motion dysfunction of patients with cervical spondylotic myelopathy (CSM). STUDY DESIGN/SETTING: A cross-sectional study. PATIENT SAMPLE: One hundred forty consecutive healthy individuals (70 men and 70 women) and 120 CSM patients (60 men and 60 women) were enrolled in the present study. OUTCOME MEASURES: The cervical motion process parameters, including the flexion and extension ROM, the flexion and extension time, and the Japanese Orthopedic Association scores (JOA) for cervical spine were measured. METHODS: Two hundred and sixty consecutive participants were asked to wear ADCM system and then fully flex and extend their neck rapidly and evenly at tolerable maximum speed. The cervical motion process was recorded and converted into waveforms. Relevant waveform parameters were measured and analyzed. The number of complete flexion-extension motions in 10 seconds has been defined as 10s F-E cycles. The Japanese Orthopedics Association (JOA) scores of CSM patients were marked. RESULTS: CSM patients had a lower number of 10s F-E cycles than healthy subjects. There were significant differences in flexion and extension time and ROM between two groups. The waveforms of myelopathy patients were wider and lower than those in healthy individuals. The average ratio value (defined as F) of wave height to wave width (a+b/c+d) could quantitatively reflect such differences of waveforms. The average F value was correlated with the JOA scores of the cervical motion function (r=0.7538), and F value declined as JOA scores decreased. According to receiver operating characteristic curve analysis, the optimal threshold value of the normal average ratio was more than 34.7. CONCLUSIONS: ADCM appears to be an objective and quantitative severity assessment tool for confirmed CSM patients by evaluating dynamic cervical spine motion dysfunction.

[Temporal Evolution and Main Influencing Factors of Black Carbon Aerosol in Nanjing].

Temporal evolution of black carbon (BC) in Nanjing was studied along with its main influencing factors. The multi-wavelength aethalometer (AE-33) was used to select the typical month of each season to observe BC mass concentration, combined with atmospheric pollutant data, meteorological elements, and boundary layer detection data. Seasonal, daily, weekly trends, and source characteristics of BC were analyzed. The results showed that the BC concentration in Nanjing had obvious seasonal changes, which were higher in spring and winter, in the decreasing order:spring[(3351±919) ng·m-3] > winter[(3234±2102) ng·m-3] > in autumn[(3064±967) ng·m-3] > summer[(2632±1705) ng·m-3]. The diurnal changes in BC during the four seasons are bimodal, with peaks at 06:00-08:00 and 21:00-23:00. The morning and evening peak distribution characteristics of BC in different seasons are different. The peak concentration of BC was highest in the early morning peak spring and the highest in the late peak winter. The morning peak timing of winter is 2 h behind other seasons, while the summer peak timing is 2 h ahead of other seasons. The effect of the wind speed on the seasonal distribution of BC diurnal variation is significantly larger than that on RH. The mechanism of the influence of the inversion layer on the concentration of atmospheric pollutants is complicated. The effects of height, thickness, and temperature of the inversion layer on the pollutants are different in different seasons. Weekly BC effects vary seasonally. The effect of RH and wind speed on the weekly BC effect is small, and the difference in the inversion layer is the main reason behind it. Liquid fuel combustion in Nanjing has a greater contribution to BC, whereas solid combustion contributes by a lesser extent.

Study on Rheological Behavior and Surface Properties of Epoxy Resin Chemical Grouting Material Considering Time Variation.

Epoxy resins are widely used for repairing cracks in stone, mortar and masonry. A main factor that influences the grouting quality is the permeability of grout. However, the permeability will deteriorate over time because of the reaction of chemical grouting materials, which will greatly affect the results of grouting. To the best of our knowledge, there are few reports that focus on the time-varying properties of viscosity and affinity of epoxy resins grouting material. In this paper, we investigate the changing rules of viscosity and affinity with time by studying the viscosity, surface tension and contact angle of the epoxy grouting material. We establish the mathematical model for the time-dependent properties of CW epoxy resin on viscosity and affinity with experimental verification. Moreover, we make a detailed discussion on the modeling of viscosity variation considering both time and temperature. The results show important guiding significance and application value for judging the grout irrigability in the construction process.

Variation over time in wing size and shape of the coastal malaria vector Anopheles (Cellia) epiroticus Linton and Harbach (Diptera: Culicidae) in Samut Songkhram, Thailand.

OBJECTIVE: Anopheles (Cellia) epiroticus Linton & Harbach, a coastal mosquito (also called a brackish mosquito), is a secondary vector species of malaria distributed throughout eastern and southern regions of Thailand. This research aimed to investigate the differences of wing size and shape of this female Aonpheles species in Samut Songkhram Province, Thailand occurring over time between 2015 and 2017. MATERIALS AND METHODS: Coordinates of 13 landmarks were selected and digitized. Centroid size (CS) was used to estimate wing size. Shape variables were used to estimate wing shape and were calculated from the Generalized Procrustes Analysis following principal components of the partial warp. The statistically significant differences of the average wing size based on CS and wing shape based on Mahalanobis distances in each year were estimated using the non-parametric permutation testing with 1,000 cycles after Bonferroni correction with a significance level of 0.05 (p < 0.05). RESULTS: The A. epiroticus population in year 2016 had the highest average (3.61 mm), and the population in year 2017 had the lowest (3.47 mm). In this study, there was no difference in the size of wing between A. epiroticus population in the years 2015 and 2016 (p > 0.05). The A. epiroticus population in year 2017 was significantly smaller than the population in the years 2015 and 2016 (p < 0.05). All pairwise comparisons of wing shape Mahalanobis distances were significantly different in year 2017 compared with 2015 and 2016 (p < 0.01). CONCLUSION: These results indicate differences of wings occur over time that affect the morphological variability of A. epiroticus. The differences in weather conditions in each year affect the adaptive and morphological changes of mosquitoes in coastal areas.

It's about time: Cesarean sections and neonatal health.

Cesarean sections have been associated in the literature with poorer newborn health, particularly with a higher incidence of respiratory morbidity. Most studies suffer, however, from potential omitted variable bias, as they are based on simple comparisons of mothers who give birth vaginally and those who give birth by cesarean section. We try to overcome this limitation and provide credible causal evidence by using variation in the probability of having a c-section that is arguably unrelated to maternal and fetal characteristics: variation by time of day. Previous literature documents that, while nature distributes births and associated problems uniformly, time-dependent variables related to physicians' demand for leisure are significant predictors of unplanned c-sections. Using a sample of public hospitals in Spain, we show that the rate of c-sections is higher during the early hours of the night compared to the rest of the day, while mothers giving birth at the different times are similar in observable characteristics. This exogenous variation provides us with a new instrument for type of birth: time of delivery. Our results suggest that non-medically indicated c-sections have a negative and significant impact on newborn health, as measured by Apgar scores, but that the effect is not severe enough to translate into more extreme outcomes.

The effect of age and microstructural white matter integrity on lap time variation and fast-paced walking speed.

Macrostructural white matter damage (WMD) is associated with less uniform and slower walking in older adults. The effect of age and subclinical microstructural WM degeneration (a potentially earlier phase of WM ischemic damage) on walking patterns and speed is less clear. This study examines the effect of age on the associations of regional microstructural WM integrity with walking variability and speed, independent of macrostructural WMD. This study involved 493 participants (n = 51 young; n = 209 young-old; n = 233 old-old) from the Baltimore Longitudinal Study of Aging. All completed a 400-meter walk test and underwent a concurrent brain MRI with diffusion tensor imaging. Microstructural WM integrity was measured as fractional anisotropy (FA). Walking variability was measured as trend-adjusted variation in time over ten 40-meter laps (lap time variation, LTV). Fast-paced walking speed was assessed as mean lap time (MLT). Multiple linear regression models of FA predicting LTV and MLT were adjusted for age, sex, height, weight, and WM hyperintensities. Independent of WM hyperintensities, lower FA in the body of the corpus callosum was associated with higher LTV and longer MLT only in the young-old. Lower FA in superior longitudinal, inferior fronto-occipital, and uncinate fasciculi, the anterior limb of the internal capsule, and the anterior corona radiate was associated with longer MLT only in the young-old. While macrostructural WMD is known to predict more variable and slower walking in older adults, microstructural WM disruption is independently associated with more variable and slower fast-paced walking only in the young-old. Disrupted regional WM integrity may be a subclinical contributor to abnormal walking at an earlier phase of aging.

Lower gray matter integrity is associated with greater lap time variation in high-functioning older adults.

BACKGROUND: Lower integrity of cerebral gray matter is associated with higher gait variability. It is not known whether gray matter integrity is associated with higher lap time variation (LTV), a clinically accessible measure of gait variability, high levels of which have been associated with mortality. This study examines the cross-sectional association between gray matter mean diffusivity (MD) and LTV in community-dwelling older adults. METHODS: Study participants consisted of 449 high-functioning adults aged 50 and older (56.8% female) in the Baltimore Longitudinal Study of Aging, free of overt neurological disease. The magnitude of MD in the gray matter, a measure of impaired tissue integrity, was assessed by diffusion tensor imaging in 16 regions of interest (ROIs) involved with executive function, sensorimotor function, and memory. LTV was assessed as variability in lap time based on individual trajectories over ten 40-m laps. Age, sex, height, and weight were covariates. The model additionally adjusted for mean lap time and health conditions that may affect LTV. RESULTS: Higher levels of average MD across 16 ROIs were significantly associated with higher LTV after adjustment for covariates. Specifically, higher MD in the precuneus and the anterior and middle cingulate cortices was strongly associated with higher LTV, as compared to other ROIs. The association persisted after adjustment for mean lap time, hypertension, and diabetes. CONCLUSIONS: Lower gray matter integrity in selected areas may underlie greater LTV in high-functioning community-dwelling older adults. Longitudinal studies are warranted to examine whether changes in gray matter integrity precede more variable gait.