An authoritative parenting style has been shown to promote children’s emotion regulation in European-American family studies.However,little is known about how sleep problems and the child’s sibling status in Chinese...An authoritative parenting style has been shown to promote children’s emotion regulation in European-American family studies.However,little is known about how sleep problems and the child’s sibling status in Chinese families affect this relationship.Based on family system theory,this study attempts to better understand the relationship between authoritative parenting style and emotion regulation.Mothers of preschool children in Chinese kindergartens completed questionnaires about their children’s sleep habits,their authoritative parenting styles,and children’s emotion regulation.A total of 531 children participated in this study.Results showed that authoritative parenting was positively associated with emotional regulation.Sleep problems mediated the effects of authoritative parenting style on emotion regulation.The child’s sibling status moderated the mediating effects of sleep problems in authoritative parenting and emotion regulation relationships.Specifically,the relationship between the authoritative parenting style and sleep problems was significant for only children,while birth order had no significant influence on the authoritative parenting style and sleep problems in two-child families.These findings suggest that a lowauthoritative parenting style predicts low emotion regulation through sleep problems,and this depends on the child’s sibling status,indicating that children without siblings may impair emotion regulation due to increased sleep problems.展开更多
On July 29, 2021, a large earthquake of MW8.2 occurred south of the Alaska Peninsula. To investigate the spatial-temporal changes of crustal stress in the earthquake-stricken area before this event, we selected 159 ea...On July 29, 2021, a large earthquake of MW8.2 occurred south of the Alaska Peninsula. To investigate the spatial-temporal changes of crustal stress in the earthquake-stricken area before this event, we selected 159 earthquakes of 4.7 ≤ MW ≤ 6.9 that occurred in the epicentral region and its surroundings between January 1980 and June 2021 to study the temporal variation and spatial distribution of their apparent stress. In addition, we analyzed the correlation between seismic activities and Earth’s rotation and explored the seismogenic process of this earthquake. The crustal stress rose from January 2008 to December 2016. This period was followed by a sub-instability stage from January 2017 until the occurrence of the MW8.2 earthquake. The average rate of apparent stress change in the first five years of the stress increase period was roughly 2.3 times that in the last four years. The lateral distribution of the apparent stress shows that the areas with apparent stress greater than 1.0 MPa exhibited an expanding trend during the seismogenic process. The maximum apparent stress was located at the earthquake epicenter during the last four years. The distribution of the apparent stress in the E-W vertical cross section revealed that an apparent stress gap formed around the hypocenter during the first five years of the stress increase period, surrounded by areas of relatively high apparent stress. After the Alaska earthquake, most parts of this gap were filled in by aftershocks. The seismic activities during the sub-instability stage exhibited a significant correlation with Earth’s rotation.展开更多
BACKGROUND Disease knowledge is associated with increased treatment compliance and improvement of symptoms in inflammatory bowel disease(IBD).IBD-knowledge inventory device(IBD-KID)was developed and validated specific...BACKGROUND Disease knowledge is associated with increased treatment compliance and improvement of symptoms in inflammatory bowel disease(IBD).IBD-knowledge inventory device(IBD-KID)was developed and validated specifically as a tool to measure disease-related knowledge in children with IBD and their parents.AIM To prospectively assess the determinants of disease-related knowledge regarding paediatric IBD patients and their parents,using the IBD-KID.METHODS A questionnaire-based survey was carried out in paediatric patients and their parents.The determinants of patients’and parents’IBD-KID scores were assessed according to hierarchical linear regression models.RESULTS The study group consisted of 269 IBD patients and 298 parents.The patients’mean(standard deviation,SD)IBD-KID score was 10.87(±3.97),while the parents’was 11.95(±3.97).Both groups exhibited poor knowledge of the side effects of steroid therapy,the role of surgical treatment in IBD,dietary restrictions and the risks associated with the use of herbal medicines.The patients’IBD-KID scores were statistically associated with patient sex[B coefficient(standard error,SE)=1.03(0.44),P=0.021]and patient age[B(SE)=0.03(0.01),P<0.001].The parents’IBD-KID scores were significantly related to patient age[B(SE)=0.02(0.01),P=0.003],and treatment with immunosuppressive agent[B(SE)=1.85(0.48),P<0.001].The final models explained 26.9%of the variance of patients’IBD-KID scores and 18.5%of the variance of parents’scores.CONCLUSION The variables originating from parents’knowledge were significantly associated with patients’IBD-KID scores.The study results indicate the need to implement better education programmes for patients and parents.展开更多
Purpose and Topic: A longer life expectancy is expected to rise continuously in all populations on all continents. Older parents are at risk of having to accompany their adult children through a severe illness, somet...Purpose and Topic: A longer life expectancy is expected to rise continuously in all populations on all continents. Older parents are at risk of having to accompany their adult children through a severe illness, sometimes even to their death. The present study investigates the experiences of being a parent to an adult child with a severe illness and what support was helpful during the child's period of illness. Method: A qualitative approach with in-depth interviews which were analyzed using content analysis. Results: The results showed that a common perception was that it is very special to have a child with a severe illness. The underlying elements of existential experience and the relationship both influenced the parents' conceptions of life and permeated the whole situation. There were four areas that the parents found important and influenced how they could manage the situation: having information, participation, strategies to cope with the situation, and support. Conclusions: Accompanying an adult child through a severe and potentially fatal disease in the context of a growing elderly population will become an increasingly frequent problem. So far there is limited research in this area and more research should be a high priority in the future.展开更多
The amount of data that is traveling across the internet today, including very large and complex set of raw facts that are not only large, but also, complex, noisy, heterogeneous, and longitudinal data as well. Compan...The amount of data that is traveling across the internet today, including very large and complex set of raw facts that are not only large, but also, complex, noisy, heterogeneous, and longitudinal data as well. Companies, institutions, healthcare system, mobile application capturing devices and sensors, traffic management, banking, retail, education etc., use piles of data which are further used for creating reports in order to ensure continuity regarding the services that they have to offer. Recently, Big data is one of the most important topics in IT industry. Managing Big data needs new techniques because traditional security and privacy mechanisms are inadequate and unable to manage complex distributed computing for different types of data. New types of data have different and new challenges also. A lot of researches treat with big data challenges starting from Doug Laney’s landmark paper</span><span style="font-family:Verdana;">,</span><span style="font-family:Verdana;"> during the previous two decades;the big challenge is how to operate a huge volume of data that has to be securely delivered through the internet and reach its destination intact. The present paper highlights important concepts of Fifty</span><span style="font-family:Verdana;">-</span><span style="font-family:Verdana;">six Big Data V’s characteristics. This paper also highlights the security and privacy Challenges that Big Data faces and solving this problem by proposed technological solutions that help us avoiding these challenging problems.展开更多
The purpose of this article is to demonstrate the impact on children's development from parents and siblings differed in many aspects through literature review. From the literature review, it shows that parents an...The purpose of this article is to demonstrate the impact on children's development from parents and siblings differed in many aspects through literature review. From the literature review, it shows that parents and siblings contribute differently to children's emotional, social and cognitive development to some extent. Besides,it seems that having a sibling is more likely to benefit the younger siblings, not the older one.展开更多
Objectives: This study empirically assesses the impact of the changes in women’s characteristics, empowerment, availability and quality of health services on woman’s decision to use antenatal care (ANC) and the freq...Objectives: This study empirically assesses the impact of the changes in women’s characteristics, empowerment, availability and quality of health services on woman’s decision to use antenatal care (ANC) and the frequency of that use during the period 2000-2008. Study Design: The study is a cross-sectional analytical study using 2000 and 2008 Egypt Demographic and Health Surveys. Methods: The assessment of the studied impact is conducted using the Zero-inflated Negative Binomial Regression. In addition, Factor Analysis technique is used to construct some of the explanatory variables such as women’s empowerment, the availability and quality of health services indicators. Results: Utilization of antenatal health care services is greatly improved from 2000 to 2008. Availability of health services is one of the main determinants that affect the number of antenatal care visits in 2008. Wealth index and quality of health services play an important role in raising the level of antenatal care utilization in 2000 and 2008. However, the impact of the terminated pregnancy on receiving ANC increased over time. Conclusions: Further research of the determinants of antenatal health care utilization is needed, using more updated measures of women’s empowerment, availability and quality of health services. In order to improve the provision of antenatal health care services, it is important to understand barriers to antenatal health care utilization. Therefore, it is advisable to collect information from women about the reasons for not receiving antenatal care.展开更多
Current research on pump-turbine units is focused on the unstable operation at off-design conditions, with the characteristic curves in generating mode being S-shaped. Unlike in the traditional water turbines, pump-tu...Current research on pump-turbine units is focused on the unstable operation at off-design conditions, with the characteristic curves in generating mode being S-shaped. Unlike in the traditional water turbines, pump-turbine operation along the S-shaped curve can lead to difficulties during load rejection with unusual increases in the water pressure, which leads to machine vibrations. This paper describes both model tests and numerical simulations. A reduced scale model of a low specific speed pump-turbine was used for the performance tests, with comparisons to computational fluid dynamics(CFD) results. Predictions using the detached eddy simulation(DES) turbulence model, which is a combined Reynolds averaged Naviers-Stokes(RANS) and large eddy simulation(LES) model, are compared with the two-equation turbulence mode results. The external characteristics as well as the internal flow are for various guide vane openings to understand the unsteady flow along the so called S characteristics of a pump-turbine. Comparison of the experimental data with the CFD results for various conditions and times shows that DES model gives better agreement with experimental data than the two-equation turbulence model. For low flow conditions, the centrifugal forces and the large incident angle create large vortices between the guide vanes and the runner inlet in the runner passage, which is the main factor leading to the S-shaped characteristics. The turbulence model used here gives more accurate simulations of the internal flow characteristics of the pump-turbine and a more detailed force analysis which shows the mechanisms controlling of the S characteristics.展开更多
In order to reflect the influence of the drivers' characteristic differences on intersection capacity under a mixed traffic flow, a driver correction coefficient for the intersection capacity calculation according to...In order to reflect the influence of the drivers' characteristic differences on intersection capacity under a mixed traffic flow, a driver correction coefficient for the intersection capacity calculation according to the driver's visual characteristics is proposed. First, the parameters of the driver's visual characteristics at some real roads, including gaze fixation distribution, mean fixation duration, visual angle distribution and some other parameters at intersections, are collected. Then, the relationship between the traffic flow rate at intersections and the parameters of driver eye movements are established. The analytical results indicate that when the traffic flow is unsaturated, the parameters of driver eye movements change relatively little; however, when the traffic flow is saturated, the parameters of driver eye movements change drastically. Finally, the saturation-flow-rate model is modified according to the parameters of driver eye movements; thus, a capacity model of intersections considering the driver's visual characteristics is obtained.展开更多
Background: Seasonal influenza epidemic occurs every year in Guangzhou, which can affect all age groups. Young children are the most susceptible targets. Parents can decide whether to vaccinate their children or not ...Background: Seasonal influenza epidemic occurs every year in Guangzhou, which can affect all age groups. Young children are the most susceptible targets. Parents can decide whether to vaccinate their children or not based on their own consideration in China. The aim of this study was to identify factors that are important for parental decisions on vaccinating their children against seasonal influenza based on a modified health belief model (HBM). Methods: A cross-sectional study was conducted in Guangzhou, China. A total of 335 parents who had at least on child aged between 6 months and 3 years were recruited from women and children's hospital in Guangzhou, China. Each eligible subject was invited for a face-to-face interview based on a standardized questionnaire. Results: Uptake of seasonal influenza within the preceding 12 months among the target children who aged between 6 months and 36 months was 47.7%. Around 62.4% parents indicated as being "likely/very likely" to take their children for seasonal influenza vaccination in the next 12 months. The hierarchical logistic regression model showed that children's age (odds ratio [OR] =2.59, 95% confidence interval [C/I: 1.44-4.68), social norm (OR = 2.08, 95% CI: 1.06-4.06) and perceived control (OR - 2.96, 95% CI: 1.60-5.50) were significantly and positively associated with children's vaccination uptake within the preceding 12 months; children with a history of taking seasonal influenza vaccine (OR = 2.50, 95% CI: 1.31-4.76), perceived children's health status (OR = 3.36, 95% C1: 1.68-6.74), worry/anxious about their children influenza infection (OR = 2.31, 95% CI: 1.19-4.48) and perceived control (OR = 3.21, 95% CI: 1.65-6.22) were positively association with parental intention to vaccinate their children in the future 12 months. However, anticipated more regret about taking children for the vaccination was associated with less likely to vaccinate children within the preceding 12 months (OR = 0.21, 95% CI: 0.08-0.52). Conclusions: The modified HBM provided a good theoretical basic for understanding factors associated with parents' decisions on their children's vaccination against seasonal influenza.展开更多
Background: Child labour is a big problem. Studies have indicated several problems of child labour. However, few studies have indicated the characteristics of child labour rural India. Objectives: This study has explo...Background: Child labour is a big problem. Studies have indicated several problems of child labour. However, few studies have indicated the characteristics of child labour rural India. Objectives: This study has explored characteristics of child labour and their families in the rural community of eastern India and also identified their health problems. Methods: A cross-sectional study was designed to explore their characteristics in purposively selected areas in rural Howrah, India. Frequency table and bar-diagrams were used. Results: The study identified 72% boys and 28% girls as child labour. Majority of the children (67.9%) were labour because they wanted to help their parents. In 8.9% cases, they were forced to work by their parents. In 5.4% cases, they were orphans. Majority of the children were not satisfied (78.6%) with their job place and job status. Conclusions: Child labourers are not satisfied with their job. Their money is used in family. Parents are illiterate. Lack of effective education system and availability of functional schools are both causes and consequences of child labour. Due to illiteracy, working conditions for these children get worse as they are not even aware of the occupational benefits.展开更多
In an evolutionary perspective individuals are expected to vary the degree of parental love and care in relation to the fitness value that a child represents. Hence, stepparents are expected to show less solicitude th...In an evolutionary perspective individuals are expected to vary the degree of parental love and care in relation to the fitness value that a child represents. Hence, stepparents are expected to show less solicitude than genetically related parents, and this lack of genetic relatedness has been used to explain the higher frequencies of child abuse and homicide found in stepfamilies. However, other factors than non-genetic relatedness may cause this over-representation in stepfamilies. Here we use a 45-year data set of parental chiltl homicides in Sweden to test two hypotheses related to the higher incidence in stepfamilies: 1) adults in different types of family differ in their general disposition to use violence, and 2) parents are more likely to kill stepchildren than genetically related children. Of the 152 perpetrators in biparental families there was an overrepresentation of perpetrators in step- families (n=27) compared with the general population. We found support for the first hypothesis in that both general and violent crime rates were higher in stepfamilies, both in the general population and among perpetrators of child homicide. However, we found no support for the second hypothesis because of the 27 perpetrators in stepfamilies the perpetrator killed a genetically related child in 13 cases, a stepchild in 13 cases and both types of children in one case. Moreover, out of the 12 families where the perpetrator lived with both stepchildren and genetic children, there was no bias towards killing stepchildren. Thus, we found no evidence for an effect of non-genetic relatedness per se [Current Zoology 57 (3): 253-259, 2011].展开更多
Water blooms have become a worldwide environmental problem. Recently, algicidal bacteria have attracted wide attention as possible agents for inhibiting algal water blooms. In this study, one strain of algicidal bacte...Water blooms have become a worldwide environmental problem. Recently, algicidal bacteria have attracted wide attention as possible agents for inhibiting algal water blooms. In this study, one strain of algicidal bacterium B5 was isolated from activated sludge. On the basis of analysis of its physiological characteristics and 16S rDNA gene sequence, it was identified as Bacillusfusiformis. Its algaelysing characteristics on Microcystis aeruginosa, Chlorella and Scenedesmus were tested. The results showed that: (1) the algicidal bacterium B5 is a Gram-negative bacterium. The 16S rDNA nucleotide sequence homology of strain B5 with 2 strains of B. fusiformis reached 99.86%, so B5 was identified as B. fusiformis; (2) the algal-lysing effects of the algicidal bacterium B5 on M. aeruginosa, Chlorella and Scenedesrnus were pronounced. The initial bacterial and algal cell densities strongly influence the removal rates of chlorophyll-a. The greater the initial bacterial cell density, the faster the degradation of chlorophyll-a. The greater the initial algal cell density, the slower the degradation of chlorophyll-a. When the bacterial cell density was 3.6 × 10^7 cells/ml, nearly 90% of chlorophyll-a was removed. When the chlorophyll-a concentration was less than 550 μg/L, about 70% was removed; (3) the strain B5 lysed algae by secreting metabolites and these metabolites could bear heat treatment.展开更多
基金supported by the Guangdong Province Philosophy and Social Science Project(Grant No.GD22CJY12)the Young Innovation Talent Project of Guangdong Province(Grant No.2022WTSCX112)the Key Construction Discipline of Guangdong Province(Grant No.2022ZDJS061)to Yan Jin.
文摘An authoritative parenting style has been shown to promote children’s emotion regulation in European-American family studies.However,little is known about how sleep problems and the child’s sibling status in Chinese families affect this relationship.Based on family system theory,this study attempts to better understand the relationship between authoritative parenting style and emotion regulation.Mothers of preschool children in Chinese kindergartens completed questionnaires about their children’s sleep habits,their authoritative parenting styles,and children’s emotion regulation.A total of 531 children participated in this study.Results showed that authoritative parenting was positively associated with emotional regulation.Sleep problems mediated the effects of authoritative parenting style on emotion regulation.The child’s sibling status moderated the mediating effects of sleep problems in authoritative parenting and emotion regulation relationships.Specifically,the relationship between the authoritative parenting style and sleep problems was significant for only children,while birth order had no significant influence on the authoritative parenting style and sleep problems in two-child families.These findings suggest that a lowauthoritative parenting style predicts low emotion regulation through sleep problems,and this depends on the child’s sibling status,indicating that children without siblings may impair emotion regulation due to increased sleep problems.
基金supported by the the Special fund of the Institute of Geophysics,China Earthquake Administration(No.DQJB22Z04).
文摘On July 29, 2021, a large earthquake of MW8.2 occurred south of the Alaska Peninsula. To investigate the spatial-temporal changes of crustal stress in the earthquake-stricken area before this event, we selected 159 earthquakes of 4.7 ≤ MW ≤ 6.9 that occurred in the epicentral region and its surroundings between January 1980 and June 2021 to study the temporal variation and spatial distribution of their apparent stress. In addition, we analyzed the correlation between seismic activities and Earth’s rotation and explored the seismogenic process of this earthquake. The crustal stress rose from January 2008 to December 2016. This period was followed by a sub-instability stage from January 2017 until the occurrence of the MW8.2 earthquake. The average rate of apparent stress change in the first five years of the stress increase period was roughly 2.3 times that in the last four years. The lateral distribution of the apparent stress shows that the areas with apparent stress greater than 1.0 MPa exhibited an expanding trend during the seismogenic process. The maximum apparent stress was located at the earthquake epicenter during the last four years. The distribution of the apparent stress in the E-W vertical cross section revealed that an apparent stress gap formed around the hypocenter during the first five years of the stress increase period, surrounded by areas of relatively high apparent stress. After the Alaska earthquake, most parts of this gap were filled in by aftershocks. The seismic activities during the sub-instability stage exhibited a significant correlation with Earth’s rotation.
文摘BACKGROUND Disease knowledge is associated with increased treatment compliance and improvement of symptoms in inflammatory bowel disease(IBD).IBD-knowledge inventory device(IBD-KID)was developed and validated specifically as a tool to measure disease-related knowledge in children with IBD and their parents.AIM To prospectively assess the determinants of disease-related knowledge regarding paediatric IBD patients and their parents,using the IBD-KID.METHODS A questionnaire-based survey was carried out in paediatric patients and their parents.The determinants of patients’and parents’IBD-KID scores were assessed according to hierarchical linear regression models.RESULTS The study group consisted of 269 IBD patients and 298 parents.The patients’mean(standard deviation,SD)IBD-KID score was 10.87(±3.97),while the parents’was 11.95(±3.97).Both groups exhibited poor knowledge of the side effects of steroid therapy,the role of surgical treatment in IBD,dietary restrictions and the risks associated with the use of herbal medicines.The patients’IBD-KID scores were statistically associated with patient sex[B coefficient(standard error,SE)=1.03(0.44),P=0.021]and patient age[B(SE)=0.03(0.01),P<0.001].The parents’IBD-KID scores were significantly related to patient age[B(SE)=0.02(0.01),P=0.003],and treatment with immunosuppressive agent[B(SE)=1.85(0.48),P<0.001].The final models explained 26.9%of the variance of patients’IBD-KID scores and 18.5%of the variance of parents’scores.CONCLUSION The variables originating from parents’knowledge were significantly associated with patients’IBD-KID scores.The study results indicate the need to implement better education programmes for patients and parents.
文摘Purpose and Topic: A longer life expectancy is expected to rise continuously in all populations on all continents. Older parents are at risk of having to accompany their adult children through a severe illness, sometimes even to their death. The present study investigates the experiences of being a parent to an adult child with a severe illness and what support was helpful during the child's period of illness. Method: A qualitative approach with in-depth interviews which were analyzed using content analysis. Results: The results showed that a common perception was that it is very special to have a child with a severe illness. The underlying elements of existential experience and the relationship both influenced the parents' conceptions of life and permeated the whole situation. There were four areas that the parents found important and influenced how they could manage the situation: having information, participation, strategies to cope with the situation, and support. Conclusions: Accompanying an adult child through a severe and potentially fatal disease in the context of a growing elderly population will become an increasingly frequent problem. So far there is limited research in this area and more research should be a high priority in the future.
文摘The amount of data that is traveling across the internet today, including very large and complex set of raw facts that are not only large, but also, complex, noisy, heterogeneous, and longitudinal data as well. Companies, institutions, healthcare system, mobile application capturing devices and sensors, traffic management, banking, retail, education etc., use piles of data which are further used for creating reports in order to ensure continuity regarding the services that they have to offer. Recently, Big data is one of the most important topics in IT industry. Managing Big data needs new techniques because traditional security and privacy mechanisms are inadequate and unable to manage complex distributed computing for different types of data. New types of data have different and new challenges also. A lot of researches treat with big data challenges starting from Doug Laney’s landmark paper</span><span style="font-family:Verdana;">,</span><span style="font-family:Verdana;"> during the previous two decades;the big challenge is how to operate a huge volume of data that has to be securely delivered through the internet and reach its destination intact. The present paper highlights important concepts of Fifty</span><span style="font-family:Verdana;">-</span><span style="font-family:Verdana;">six Big Data V’s characteristics. This paper also highlights the security and privacy Challenges that Big Data faces and solving this problem by proposed technological solutions that help us avoiding these challenging problems.
文摘The purpose of this article is to demonstrate the impact on children's development from parents and siblings differed in many aspects through literature review. From the literature review, it shows that parents and siblings contribute differently to children's emotional, social and cognitive development to some extent. Besides,it seems that having a sibling is more likely to benefit the younger siblings, not the older one.
文摘Objectives: This study empirically assesses the impact of the changes in women’s characteristics, empowerment, availability and quality of health services on woman’s decision to use antenatal care (ANC) and the frequency of that use during the period 2000-2008. Study Design: The study is a cross-sectional analytical study using 2000 and 2008 Egypt Demographic and Health Surveys. Methods: The assessment of the studied impact is conducted using the Zero-inflated Negative Binomial Regression. In addition, Factor Analysis technique is used to construct some of the explanatory variables such as women’s empowerment, the availability and quality of health services indicators. Results: Utilization of antenatal health care services is greatly improved from 2000 to 2008. Availability of health services is one of the main determinants that affect the number of antenatal care visits in 2008. Wealth index and quality of health services play an important role in raising the level of antenatal care utilization in 2000 and 2008. However, the impact of the terminated pregnancy on receiving ANC increased over time. Conclusions: Further research of the determinants of antenatal health care utilization is needed, using more updated measures of women’s empowerment, availability and quality of health services. In order to improve the provision of antenatal health care services, it is important to understand barriers to antenatal health care utilization. Therefore, it is advisable to collect information from women about the reasons for not receiving antenatal care.
基金Supported by National Natural Science Foundation of China(Grant No.51139007)State Key Laboratory of Hydroscience and Engineering Open Foundation of China(Grant No.2014-KY-05)
文摘Current research on pump-turbine units is focused on the unstable operation at off-design conditions, with the characteristic curves in generating mode being S-shaped. Unlike in the traditional water turbines, pump-turbine operation along the S-shaped curve can lead to difficulties during load rejection with unusual increases in the water pressure, which leads to machine vibrations. This paper describes both model tests and numerical simulations. A reduced scale model of a low specific speed pump-turbine was used for the performance tests, with comparisons to computational fluid dynamics(CFD) results. Predictions using the detached eddy simulation(DES) turbulence model, which is a combined Reynolds averaged Naviers-Stokes(RANS) and large eddy simulation(LES) model, are compared with the two-equation turbulence mode results. The external characteristics as well as the internal flow are for various guide vane openings to understand the unsteady flow along the so called S characteristics of a pump-turbine. Comparison of the experimental data with the CFD results for various conditions and times shows that DES model gives better agreement with experimental data than the two-equation turbulence model. For low flow conditions, the centrifugal forces and the large incident angle create large vortices between the guide vanes and the runner inlet in the runner passage, which is the main factor leading to the S-shaped characteristics. The turbulence model used here gives more accurate simulations of the internal flow characteristics of the pump-turbine and a more detailed force analysis which shows the mechanisms controlling of the S characteristics.
基金The National Natural Science Foundation of China (No.50708019)Huo Yingdong Education Foundation(No.104010)Jiangsu Qing Lan Project
文摘In order to reflect the influence of the drivers' characteristic differences on intersection capacity under a mixed traffic flow, a driver correction coefficient for the intersection capacity calculation according to the driver's visual characteristics is proposed. First, the parameters of the driver's visual characteristics at some real roads, including gaze fixation distribution, mean fixation duration, visual angle distribution and some other parameters at intersections, are collected. Then, the relationship between the traffic flow rate at intersections and the parameters of driver eye movements are established. The analytical results indicate that when the traffic flow is unsaturated, the parameters of driver eye movements change relatively little; however, when the traffic flow is saturated, the parameters of driver eye movements change drastically. Finally, the saturation-flow-rate model is modified according to the parameters of driver eye movements; thus, a capacity model of intersections considering the driver's visual characteristics is obtained.
文摘Background: Seasonal influenza epidemic occurs every year in Guangzhou, which can affect all age groups. Young children are the most susceptible targets. Parents can decide whether to vaccinate their children or not based on their own consideration in China. The aim of this study was to identify factors that are important for parental decisions on vaccinating their children against seasonal influenza based on a modified health belief model (HBM). Methods: A cross-sectional study was conducted in Guangzhou, China. A total of 335 parents who had at least on child aged between 6 months and 3 years were recruited from women and children's hospital in Guangzhou, China. Each eligible subject was invited for a face-to-face interview based on a standardized questionnaire. Results: Uptake of seasonal influenza within the preceding 12 months among the target children who aged between 6 months and 36 months was 47.7%. Around 62.4% parents indicated as being "likely/very likely" to take their children for seasonal influenza vaccination in the next 12 months. The hierarchical logistic regression model showed that children's age (odds ratio [OR] =2.59, 95% confidence interval [C/I: 1.44-4.68), social norm (OR = 2.08, 95% CI: 1.06-4.06) and perceived control (OR - 2.96, 95% CI: 1.60-5.50) were significantly and positively associated with children's vaccination uptake within the preceding 12 months; children with a history of taking seasonal influenza vaccine (OR = 2.50, 95% CI: 1.31-4.76), perceived children's health status (OR = 3.36, 95% C1: 1.68-6.74), worry/anxious about their children influenza infection (OR = 2.31, 95% CI: 1.19-4.48) and perceived control (OR = 3.21, 95% CI: 1.65-6.22) were positively association with parental intention to vaccinate their children in the future 12 months. However, anticipated more regret about taking children for the vaccination was associated with less likely to vaccinate children within the preceding 12 months (OR = 0.21, 95% CI: 0.08-0.52). Conclusions: The modified HBM provided a good theoretical basic for understanding factors associated with parents' decisions on their children's vaccination against seasonal influenza.
文摘Background: Child labour is a big problem. Studies have indicated several problems of child labour. However, few studies have indicated the characteristics of child labour rural India. Objectives: This study has explored characteristics of child labour and their families in the rural community of eastern India and also identified their health problems. Methods: A cross-sectional study was designed to explore their characteristics in purposively selected areas in rural Howrah, India. Frequency table and bar-diagrams were used. Results: The study identified 72% boys and 28% girls as child labour. Majority of the children (67.9%) were labour because they wanted to help their parents. In 8.9% cases, they were forced to work by their parents. In 5.4% cases, they were orphans. Majority of the children were not satisfied (78.6%) with their job place and job status. Conclusions: Child labourers are not satisfied with their job. Their money is used in family. Parents are illiterate. Lack of effective education system and availability of functional schools are both causes and consequences of child labour. Due to illiteracy, working conditions for these children get worse as they are not even aware of the occupational benefits.
文摘In an evolutionary perspective individuals are expected to vary the degree of parental love and care in relation to the fitness value that a child represents. Hence, stepparents are expected to show less solicitude than genetically related parents, and this lack of genetic relatedness has been used to explain the higher frequencies of child abuse and homicide found in stepfamilies. However, other factors than non-genetic relatedness may cause this over-representation in stepfamilies. Here we use a 45-year data set of parental chiltl homicides in Sweden to test two hypotheses related to the higher incidence in stepfamilies: 1) adults in different types of family differ in their general disposition to use violence, and 2) parents are more likely to kill stepchildren than genetically related children. Of the 152 perpetrators in biparental families there was an overrepresentation of perpetrators in step- families (n=27) compared with the general population. We found support for the first hypothesis in that both general and violent crime rates were higher in stepfamilies, both in the general population and among perpetrators of child homicide. However, we found no support for the second hypothesis because of the 27 perpetrators in stepfamilies the perpetrator killed a genetically related child in 13 cases, a stepchild in 13 cases and both types of children in one case. Moreover, out of the 12 families where the perpetrator lived with both stepchildren and genetic children, there was no bias towards killing stepchildren. Thus, we found no evidence for an effect of non-genetic relatedness per se [Current Zoology 57 (3): 253-259, 2011].
文摘依据FFT→优化窗→IFFT思路,突破线性时频变换的窗函数积分性能桎梏,实现高性能优化窗函数的线性时频变换应用,建立新型时频变换算法——K-S变换.对信号x(t)的FFT频谱向量进行频移处理后,与该频移点下Kaiser优化窗的频谱向量进行Hadamard乘积,再将乘积结果进行FFT逆变换(IFFT),构造出K-S变换复时频矩阵,由此获得x(t)的时间-频率-幅值、时间-频率-相位三维信息;给出逆变换的数学推导与局部性质、线性性质和变分辨率特性;0~150 kHz电网的稳态与时变超谐波信号仿真实验表明,K-S变换的时域、频域分辨能力均优于流行的短时傅里叶变换、S变换,具有优良的变分辨率性能;0~40 kHz超谐波信号的实测证明,基于K-S变换的超谐波电压幅值测量绝对误差均小于0.032 3 V.
基金Project supported by the Special Funds for Doctor's Station of University(No.20060246024)Young Fund of Fudan University,and the Shanghai Tongji Gao Tingyao Environmental Science and Technology Developmem Fundation
文摘Water blooms have become a worldwide environmental problem. Recently, algicidal bacteria have attracted wide attention as possible agents for inhibiting algal water blooms. In this study, one strain of algicidal bacterium B5 was isolated from activated sludge. On the basis of analysis of its physiological characteristics and 16S rDNA gene sequence, it was identified as Bacillusfusiformis. Its algaelysing characteristics on Microcystis aeruginosa, Chlorella and Scenedesmus were tested. The results showed that: (1) the algicidal bacterium B5 is a Gram-negative bacterium. The 16S rDNA nucleotide sequence homology of strain B5 with 2 strains of B. fusiformis reached 99.86%, so B5 was identified as B. fusiformis; (2) the algal-lysing effects of the algicidal bacterium B5 on M. aeruginosa, Chlorella and Scenedesrnus were pronounced. The initial bacterial and algal cell densities strongly influence the removal rates of chlorophyll-a. The greater the initial bacterial cell density, the faster the degradation of chlorophyll-a. The greater the initial algal cell density, the slower the degradation of chlorophyll-a. When the bacterial cell density was 3.6 × 10^7 cells/ml, nearly 90% of chlorophyll-a was removed. When the chlorophyll-a concentration was less than 550 μg/L, about 70% was removed; (3) the strain B5 lysed algae by secreting metabolites and these metabolites could bear heat treatment.