Multiagent Continual Coordination via Progressive Task Contextualization.

Cooperative multiagent reinforcement learning (MARL) has attracted significant attention and has the potential for many real-world applications. Previous arts mainly focus on facilitating the coordination ability from different aspects (e.g., nonstationarity and credit assignment) in single-task or multitask scenarios, ignoring the stream of tasks that appear in a continual manner. This ignorance makes the continual coordination an unexplored territory, neither in problem formulation nor efficient algorithms designed. Toward tackling the mentioned issue, this article proposes an approach, multiagent continual coordination via progressive task contextualization (MACPro). The key point lies in obtaining a factorized policy, using shared feature extraction layers but separated independent task heads, each specializing in a specific class of tasks. The task heads can be progressively expanded based on the learned task contextualization. Moreover, to cater to the popular centralized training with decentralized execution (CTDE) paradigm in MARL, each agent learns to predict and adopt the most relevant policy head based on local information in a decentralized manner. We show in multiple multiagent benchmarks that existing continual learning methods fail, while MACPro is able to achieve close-to-optimal performance. More results also disclose the effectiveness of MACPro from multiple aspects, such as high generalization ability.

Sexual-Related Knowledge, School and Family Sexuality Education and Its Association with Experience of Sexual Intercourse among Vocational Secondary School Students in China.

OBJECTIVES: To investigate the associations between sexual-related knowledge, access to school and family sexuality education, and the experience of sexual intercourse, in order to make recommendations on sexuality education for vocational secondary school students in China. METHODS: A cross-sectional study was conducted among 3180 vocational secondary school students in the Shanghai municipality and the Shaanxi province, China. Data were collected through an online, electronic questionnaire, which included socio-demographics, sexual-related knowledge, sources of information, and sexual-related behaviors. RESULTS: The score on sexual-related knowledge among girls (53.8) is higher than that of boys (48.8), and that of participants from Shanghai (55.2) is higher than their counterparts from Shaanxi (47.6). The proportions of girls (70% and 41.7%, respectively) and participants from Shanghai (65% and 35.7%, respectively) who reported acquiring sexual information from their schools/teachers and parents are higher than that of boys (54.3% and 21.0%, respectively) and their counterparts from Shaanxi (59.7% and 27.4%, respectively). About 6% of participants had experienced sexual intercourse and 10% had watched porn actively. Experience of sexual intercourse was associated with higher sexual-related knowledge scores (OR = 1.01, 95% CI: 1.00-1.02) and active porn watching (OR = 2.63, 95% CI: 1.79-3.84) but was not associated with school and family sexuality education. CONCLUSIONS: Vocational secondary school students had poor sexual knowledge and inadequate school and family sexuality education. School and family-based comprehensive sexuality education should be promoted among vocational secondary school students.

Parenting Practice Profiling and Its Associated Factors among Secondary Vocational School Students in China.

BACKGROUND: Parenting styles have a tremendous influence on a child's development and behavior. Studies on parenting styles using latent profile analysis have been increasing in recent years. However, there are few such studies conducted in China, especially concerning joint parenting styles (that simultaneously characterize maternal and paternal practices), which are held over the age group of secondary vocational school students. This study aimed to identify the profiles of parenting styles and their associated factors among the parents of secondary vocational school students in China, based on natural samples and not a predetermined model. METHOD: Data were drawn from a cross-sectional study conducted among 3180 students from six secondary vocational schools in Shanghai Municipality and Shaanxi Province. A total of 2392 students who have lived with their parents for most of their lifetime were included in the study. Latent profile analysis was used to identify the profiles of parenting styles of the respondent's parents. Multinominal logistic regression models were used to examine the association between parenting style and demographic characteristics and family background and adolescent outcomes. RESULTS: We identified five latent profiles: "free-range parenting" (27.05%), "behavioral monitoring parenting" (33.65%), "authoritative parenting" (11.75%), "psychological control parenting" (14.38%) and "tiger parenting" (13.17%). The associations between these profiles and adolescent outcomes indicated that these profiles were rational. Participants' gender, grade, residential area, family economic level, parental marital relationship, and parental educational level were predictive factors for parenting styles. CONCLUSIONS: The parenting styles held over secondary vocational school students were somewhat different from Baumrind's parenting style model. A considerable number of students received a parenting style that might predispose them to behavioral and mental health outcomes and merit a tailored intervention using the predictive factors of parenting styles.

Association between sexting and mental health among secondary vocational school students / 中国学校卫生

Objective@#To explore the prevalence of sexting among secondary vocational school students and to examine the correlation between sexting and mental health, so as to provide evidence for prevention and intervention on adolescents mental health.@*Methods@#In April 2021, three secondary vocational schools from central urban area, outskirts and outer suburbs in Shanghai, among 1 580 students were selected by cluster sampling.@*Results@#The proportions of students who received and who forwarded others private photos or videos were 11.96% and 2.78%, respectively. The proportion of students who sent others personal photos or videos was 2.54%. And the proportions of boys were higher than those of girls ( χ 2=45.89, 24.09, 6.66, P <0.01). The results of multivariable Logistic analysis showed that compared with those who had never sexted, students who had ever had any sexting were at higher risk of anxiety ( OR=2.40, 95%CI =1.59-3.61), depression( OR=1.86, 95%CI =1.25-2.75), non suicidal self injury intention ( OR=2.34, 95%CI =1.48-3.69) and suicidal intention ( OR=2.96, 95%CI =1.83-4.79)( P < 0.05 ).@*Conclusion@#There is a significant correlation between sexting and mental health among secondary vocational school students. The latent risks of sexting should be included in the curriculum of comprehensive sex education for teenagers to enhance their media literacy and decision making capability, so as to prevent sexual assault or abuse caused by sexting and promote sexual and reproductive health and as well as mental health of adolescents.

Spatiotemporal analysis and potential impact factors of vegetation variation in the karst region of Southwest China.

The karst region of Southwest China is one of the largest in the world. Due to the effects of human activities and climate change, rocky desertification has become the primary ecological disaster which has significantly hindered the economic growth in Southwest China. In recent decades, the Chinese government has carried out a number of ecological restoration projects in Southwest China. This study aims to analyze the changes in vegetation coverage and its main driving factors in the Southwest China and the karst region of Southwest China from 2001 to 2015 through trend analysis, Hurst index correlation analysis, correlation analysis, and residual analysis. The results showed that (1) both Southwest China and the karst region of Southwest China experienced significant increasing trends in annual fractional vegetation cover, at a rate of 0.0028 year-1 and 0.0029 year-1, respectively; (2) the NDVI of the Southwest China and the karst region of Southwest China was stable, and the vegetation coverage areas showed low to medium fluctuations, accounting for 97.17% and 98.32% respectively; (3) the NDVI of the Southwest China and the karst region of Southwest China had strong sustainability, and the sustainable and improved regions account for 74.79% and 75.77% respectively; and (4) climate change had little influence on vegetation restoration, and human activities had a great influence on vegetation restoration. The relative contribution rates of human activities and climate change to vegetation NDVI changes in the Southwest China were 86% and 14%, respectively, and 90% and 10% in karst regions of Southwest China. Our findings contribute to a better understanding of the mechanisms of vegetation change in karst region and may provide scientific support for local vegetation restoration and conservation policies.

Exploring the long-term vegetation dynamics of different ecological zones in the farming-pastoral ecotone in northern China.

The vegetation in the farming-pastoral ecotone in northern China is influenced by both natural and anthropogenic factors and has undergone drastic changes in the past decades. The farming-pastoral ecotone is the transition zone from agriculture to animal husbandry. The ecological environment of this ecotone is complex and fragile. Most researches have primarily focused on the entire farming-pastoral ecotone, seldomly considering the differences between different ecological zones characterized by soil, climate, and biome conditions. Based on the long time series of leaf area index (LAI) data, meteorological data, and land-use dataset, this study analyzed LAI variation trends, the correlations between LAI and climate factors, and the impact of land-use type change on vegetation in the farming-pastoral ecotone in northern China. Moreover, this paper makes a full study of the changes of the whole study area from the perspective of the differences between different ecological zones. The results showed that over 36 years, areas with vegetation improvements were considerably larger than those with degradations. However, there were still 49.56% of the total area showing no significant vegetation change. There are differences in vegetation change and response to climate between the forest ecological zones and the grassland ecological zones. The vegetation improvement trends of the forest ecological zones were larger and more sensitive to temperature, while the vegetation improvements of the grassland ecological zones were relatively small, and were more sensitive to precipitation. Human activities promote LAI changes in areas close to the forest ecological zones. The change of land use indicates that the decrease of the overall natural vegetation area has not resulted in decreasing LAI. And there is a growing trend of woodland area in the grassland ecological zones. The study provides a theoretical basis for the management of the environment and vegetation in the farming-pastoral ecotone in northern China.

The socioeconomic and lifestyle determinants of contraceptive use among Chinese college students: a cross-sectional study.

BACKGROUND: Chinese youth have become more sexually active over the years, yet their behaviours of contraceptive use are influenced by socioeconomic and lifestyle factors. This study aimed to investigate the socioeconomic and lifestyle determinants of contraceptive use among Chinese college students, and to investigate quantitatively their reasons for choosing different contraceptive methods. METHODS: The study used the data from a cross-sectional survey, which was conducted in 2015 among 17,517 students from 130 colleges and professional schools in mainland China. Chi-square tests were performed to test the differences in the awareness and uses of contraceptives between male and female students. Multivariable logistic regression models were used to analyse the associations between socioeconomic and lifestyle factors and contraceptive uses. RESULTS: Condoms (95%), oral contraceptives (91%) and emergency contraceptives (71%) were the most commonly known contraceptive methods among the sample of Chinese youth that were surveyed. Among male participants, high monthly expenditure (OR = 1.37, 95%CI: 1.07-1.75), light alcohol consumption (OR = 1.47, 95%CI: 1.03-2.11), and high sexual knowledge (OR = 1.96, 95%CI: 1.57-2.45) were positively associated with contraceptive uses, while tobacco use (OR = 0.47, 95%CI: 0.23-0.95) showed a negative association with contraceptive uses. Among female students, suburban residency (OR = 1.38, 95%CI: 1.03-1.83), high level of parental education (OR = 1.96, 95%CI: 1.19-3.22), moderate alcohol consumption (OR = 2.66, 95%CI: 1.05-6.77), and high sexual knowledge (OR = 1.50, 95%CI: 1.18-1.91) were positively associated with contraceptive uses, while tobacco use (OR = 0.60, 95%CI: 0.36-0.99) showed a negative association. CONCLUSIONS: A series of socioeconomic and lifestyle factors were associated with contraceptive choices among Chinese college students. Targeted sexual education programs are in demand to improve the awareness and the use of contraceptives in this population.

ROCK inhibitor Y­27632 protects rats against cerebral ischemia/reperfusion­induced behavioral deficits and hippocampal damage.

Cerebral ischemic injury is a major cause of death and long­term disability worldwide that leads to neurological and behavioral deficits, and for which successful treatments are still lacking. Ras homolog family member A (RhoA) and Rho­associated coiled­coil containing protein kinase (ROCK) are associated with the growth of neurons and the movement of neuronal growth cones. RhoA/ROCK inhibitors have been demonstrated to promote the recovery of motor function following nerve injury, but the underlying mechanism requires further investigation. The present study aimed to investigate the effects of the ROCK inhibitor Y­27632 on middle cerebral artery occlusion (MCAO)­induced cerebral ischemic injury. Rats were randomly assigned to the Control, Y­27632, MCAO + Vehicle or MCAO + Y­27632 group. Firstly, infarct volume, cognitive ability and cerebral injury were assessed. Secondly, indicators of cerebral inflammation, oxidative stress and apoptosis were evaluated. Finally, the expression of recombinant glial fibrillary acidic protein (GFAP) and allograft inflammatory factor 1 (AIF1) in the brain were measured to assess the activation of astrocytes and microglia, respectively. The results showed that Y­27632 effectively increased the survival rate and behavioral performance of rats, and attenuated the cerebral injury, oxidative stress and cerebral inflammation levels following MCAO. The disturbance in hippocampal neurons caused by MCAO was also alleviated following treatment with Y­27632. Neuronal apoptosis was also decreased following Y­27632 treatment, as demonstrated by the TUNEL assay and the expression levels of Caspases­3, 8 and 9 and Bax/Bcl­2 ratio. The levels of GFAP and AIF1 were increased by MCAO and further promoted by Y­27632, indicating the activation of astrocytes and microglia. In conclusion, the present study offered evidence of a protective effect of Y­27632 administration on cerebral ischemia/reperfusion induced behavioral and hippocampal damage by activating astrocytes and microglia.

The relationships of school-based sexuality education, sexual knowledge and sexual behaviors-a study of 18,000 Chinese college students.

BACKGROUND: A growing prevalence of unexpected pregnancies and younger age of sexual debut is observed among Chinese young people, while they lack formal sexuality education from schools and parents. It is necessary to measure their knowledge level of sexual and reproductive health, and how such knowledge associates with their sexual behaviors and reproductive health outcomes, which would shed light on the effectiveness of sexuality education in China. METHODS: An Internet-based questionnaire survey was conducted from January to August, 2015. 130 colleges were selected from eastern, central, and western parts China with a good balance of geographic distributions. The survey link was subsequently delivered to the focal points in each college for voluntary participation, targeting on undergraduates aged 18 ~ 25. Information on demographics, experience of school-based sexuality education (defined as any course introducing information on sexual and reproductive health) and SRH knowledge quiz was collected. Multivariate linear regression and logistic regression were applied to explore the relationship between students' SRH knowledge, sexual behaviors and reproductive health outcomes, such as sexual intercourse (penetrative sex by vaginal or anal), unprotected sex, pregnancy and abortion, etc. RESULTS: A total sample of 17,966 Chinese college students (mean age = 20.2, 60.4% female) eventually entered the analysis. Only 55.6% of the respondents self-reported having received sexuality education before, and they scored significantly higher (2.33/4.00) in the SRH knowledge quiz than those who had not (1.75/4.00). Among the sexually experienced students (n = 3639, 20.2%), both males and females with higher SRH knowledge were less likely to report having experience of (partner's) pregnancy or abortion (OR < 1, p < 0.05). In the group of sexually experienced males, those with higher SRH knowledge had a slightly later age of sexual debut (coefficient = 0.28, p < 0.001), and were less likely to have unprotected sex during the last or in most sexual intercourses (OR = 0.82, 95%C.I.: 0.69 ~ 0.96). CONCLUSION: Students' experience of school-based sexuality education may be positively associated with their SRH knowledge level as well as with their sexual behaviors and reproductive health outcomes, but such associations were stronger among males than females. A more effective implementation of school-based sexuality education needs to be scaled up, and a gender-sensitive education strategy to different needs is desirable for SRH promotion among Chinese young people.

[Determination of hexavalent chromium in atmospheric particles PM2.5 and PM10 by ion chromatography with inductively coupled plasma mass spectrometry].

An analytical method using ion chromatography with inductively coupled plasma mass spectrometry (IC-ICP-MS) for the determination of hexavalent chromium (Cr(VI)) in atmospheric particles PM2.5 and PM10 was established. The Cr(VI) in the atmospheric particles was extracted ultrasonically with sodium bicarbonate solution. An anion exchange column (AG7, 50 mm x 4 mm) with 75 mmol/L ammonium nitrate solution (containing 0.22 g/L Na2EDTA, pH 7.0) as mobile phase was used for the separation. ICP-MS was used as a detector for the determination of hexavalent chromium. The calibration curve was linear in the range of 0.05-5 µg/L and the correlation coefficient was 0.999 9 for Cr(VI). The cellulose filter was fit for sampling. With the alkaline cellulose filter, the recovery of Cr(VI) increased from 75% to 102%. The recovery was complete and stable when the samples were sonicated in 20 mmol/L sodium bicarbonate solution for 30 min. The limit of quantification (LOQ) of Cr(VI) was 0.000 4 ng/m3 when the sampling volume was 20 m3. The average recoveries of Cr(VI) in the spiked PM2.5 and PM10 samples ranged from 91.6% to 102% with the relative standard deviations not more than 7.6%. The method is efficient and reliable. It can meet the requirement for the determination of Cr(VI) in atmospheric particles.

Effects of biological activity, light, temperature and oxygen on phosphorus release processes at the sediment and water interface of Taihu Lake, China.

Effects of biological activity, light, temperature and oxygen on the phosphorus (P) release processes at the sediment and water interface of a shallow lake, Taihu Lake, China, were investigated. The results show that organisms at the sediment and water interface can stimulate P release from sediments, and their metabolism can alter the surrounding micro-environmental conditions. The extent of P release and its effects on P concentration in the overlying water were affected by factors such as light, temperature and dissolved oxygen. The organism biomass increased as temperature increased, which was beneficial for P release. Dissolved total phosphorus (DTP) and dissolved inorganic phosphorus (DIP) concentrations in the corresponding overlying water were mainly controlled by light. P release occurred in both aerobic and anoxic conditions with the presence of organisms. However in the presence of light , P release in an anoxic environment was much greater than in an aerobic environment, which may stimulate alga bloom and result in an increase in total phosphorus (TP) in the overlying water. This information aids the understanding of P biogeochemical cycling at the interface and its relationship with eutrophication in shallow lakes.

Effects of organisms on the release of phosphorus at the interface between sediment and water.

Organisms at the interface between sediment and water play a significant role in the cycling of phosphorus. This study reports experimental results of the influence of organisms on phosphorus release. Results show that benthic organisms controlled the low level of phosphate in overlying water with light. The maximum phosphorus release rate can reach 7.31 mg m(-2) d(-1) without organisms, nearly twice that in a similar system with organisms. However, significant decreases in the concentrations of sodium-hydroxide-extractable phosphorus and hydrochloric-acid-extractable phosphorus were observed in the experimental system with organisms, while no significant changes were observed without organisms. In addition, the dissolved oxygen concentration in the system was higher with organisms than without organisms with light. This study is significant to the understanding of phosphorus cycling at the interface between sediment and water in lakes.

Effects of light and oxygen on the uptake and distribution of phosphorus at the sediment-water interface.

Effects of oxygen and light on the uptake and distribution of phosphorus at the sediment-water interface were investigated in this study. The experimental water and sediment samples were collected from East Taihu Lake, China. The results show that phosphorus can be taken up from the overlying water to the sediments with high nutrient loading in both anoxic and aerobic conditions. The transformation between different phosphorus fractions in the sediments and in the overlying water was observed. Effects of dissolved oxygen on the phosphorus distribution at the sediment and overlying water interface were mainly due to the inorganic processes, while effects of light were mainly due to the biological activity. This study indicates that oxygen concentration had a predominant control on the distribution and uptake of phosphorus in the sediments, and light had obvious effect on the dissolved inorganic phosphorus (DIP) concentration in the overlying water.

Effects of oxygen on the release and distribution of phosphorus in the sediments under the light condition.

Effects of oxygen on the release and distribution of phosphorus (P) in the sediments in the presence of light were investigated, using sediment cores and overlying water from Lake Taihu, in China. The results show that P can be released from sediments to the overlying water in both anoxic and aerobic conditions. But more P was released in the anoxic condition. The transformation of P between various fractions in the sediments was observed during the release experiments. Concentrations of Ca-bound P and organic P in the sediments decreased in both conditions, but Fe/Al-bound P increased in the aerobic condition. The decrease of total P and P fractions in the sediments is consistent with the accumulative increase in quantity (AIQ) of total P (TP) in the overlying water, but is contrary with the AIQ of dissolved inorganic P. This is due to the uptake of algae by the dissolved inorganic P. Total nitrogen in the sediments in the anoxic condition was lower than that in the aerobic condition, and pH in the overlying water increased in the anoxic condition.

Effects of organisms on the release of phosphorus at the interface between sediment and water.

Organisms at the interface between sediment and water play a significant role in the cycling of phosphorus. This study reports experimental results of the influence of organisms on phosphorus release. Results show that benthic organisms controlled the low level of phosphate in overlying water with light. The maximum phosphorus release rate can reach 7.31 mg m(-2) d(-1) without organisms, nearly twice that in a similar system with organisms. However, significant decreases in the concentrations of sodium-hydroxide-extractable phosphorus and hydrochloric-acid-extractable phosphorus were observed in the experimental system with organisms, while no significant changes were observed without organisms. In addition, the dissolved oxygen concentration in the system was higher with organisms than without organisms with light. This study is significant to the understanding of phosphorus cycling at the interface between sediment and water in lakes.

[Effects of illumination on overlying water quality and on phosphate adsorption by sediment].

By the method of laboratory simulation, this paper studied the effects of illumination on the quality of overlying water and on the phosphate adsorption by sediment in a clean lake region. The results showed that under anaerobic condition, illumination could increase the pH value and the dissolved oxygen (DO) concentration of overlying water, while under aerobic condition, the concentration of dissolved inorganic phosphate (DIP) in overlying water declined fast at the beginning of the experiment, which indicated that DIP concentration was controlled by the DO concentration at the water-sediment interface. With the time went on, the DIP concentration in overlying water was much lower in the light than in the dark, indicating that illumination was the dominant controlling factor to the DIP concentration in overlying water. Phosphate could be adsorbed by the sediment with continuously loading, and the adsorbed amount varied with different environmental conditions. The effect of illumination on the phosphate adsorption by sediment was limited by the environment whether being aerobic or anaerobic.