Impact of age on host responses to diet-induced obesity:Development of joint damage and metabolic set points

Background:Osteoarthritis is one of the leading causes of pain and disability worldwide,and a large percentage of patients with osteoarthritis are individuals who are also obese.In recent years,a series of animal models have demonstrated that obesity-inducing diets can result in synovial joint damage(both with and without the superimposition of trauma),which may be related to changes in percentage of body fat and a series of low-level systemic inflammatory mediators.Of note,there is a disparity between whether the dietary challenges commence at weaning,representing a weanling onset,or at skeletal maturity,representing an adult onset of obesity.We wished to evaluate the effect ofthe dietary exposure time and the age at which animals are exposed to a high-fat and high-sucrose(HFS) diet to determine whether these factors may result in disparate outcomes,as there is evidence suggesting that these factors result in differential metabolic disturbances.Based on dietary exposure time,we hypothesized that rats fed an HFS diet for 14 weeks from weaning(HFS Weanling) would demonstrate an increase in knee joint damage scores,whereas rats exposed to the HFS diet for 4 weeks,starting at 12 weeks of age(HFS Adult) and rats exposed to a standard chow diet(Chow)would not display an increase in knee joint damage scores.Methods:Male Sprague-Dawley rats were fed either an HFS diet for 14 weeks from weaning(HFS Weanling) or an HFS diet for 4 weeks,starting at 12 weeks of age(HFS Adult).At sacrifice,joints were scored using the modified Mankin Criteria,and serum was analyzed for a defined subset of inflammatory markers(Interleukin-6,leptin,monocyte chemoattractant protein-1,and tumor necrosis factorα).Results:When the HFS Weanling and HFS Adult groups were compared,both groups had a similar percent of body fat,although the HFS Weanling group had a significantly greater body mass than the HFS Adult group.The HFS Weanling and HFS Adult animals had a significant increase in body mass and percentage of body fat when compared to the Chow group.Although knee joint damage scores were low in all 3 groups,we found,contrary to our hypothesis,that the HFS Adult group had statistically significant greater knee joint damage scores than the Chow and HFS Weanling groups.Furthermore,we observed that the HFS Weanling group did not have significant differences in knee joint damage scores relative to the Chow group.Conclusion:These findings indicate that the HFS Weanling animals were better able to cope with the dietary challenge of an HFS diet than the HFS Adult group.Interestingly,when assessing various serum proinflammatory markers,no significant differences were detected between the HTS Adult and HFS Weanling groups.Although details regarding the mechanisms underlying an increase in knee joint damage scores in the HFS Adult group remain to be elucidated,these findings indicate that dietary exposure time maybe less important than the age at which an HFS diet is introduced.Moreover,increases in serum proinflammatory mediators do not appear to be directly linked to knee joint damage scores in the HFS Weanling group animals but may be partially responsible for the observed knee joint damage in the adults over the very short time of exposure to the HFS diet.     

Health-related fitness knowledge growth in middle school years: Individual- and school-level correlates

BackgroundHealth-related fitness knowledge (HRFK) has been an essential concept for many health and physical education programs. There has been limited understanding and longitudinal investigation on HRFK growth. This longitudinal study examined HRFK growth and its individual- and school-level correlates in middle school years under 1 curriculum condition: Five for Life.MethodsParticipants were 12,044 students from 47 middle schools. Data were collected at both individual/participant and school/institution levels. Individual-level variables included gender, grade, and HRFK test scores. School-level variables included percentage of students receiving free and reduced meals (FARM), student-to-faculty ratio for physical education, and school academic performance (SAP). We used hierarchical linear modeling to examine HRFK 3-year growth in relation to individual- and school-level correlates.ResultsThe average HRFK score at 6th grade for females was 42.81% ± 1.32%. The predicted HRFK growth was 17.06% ± 1.02% per year, holding other factors constant. A 1-standard deviation increase in FARM correlated with a 14.68%-point decrease in predicted test score (p = 0.02). A 1-standard deviation increase in SAP was associated with an 11.90%-point increase in HRFK score. Males had a significantly lower growth rate than females during the middle school years (0.78%/year, p = 0.02).ConclusionThe result showed that both individual- and school-level variables such as gender, FARM, and SAP influenced HRFK growth. Educators should heed gender differences in growth curves and recognize the correlates of school-level variables.     

系统动力学视域下校园足球发展及其影响因素研究

为推动我国校园足球的发展,丰富校园足球发展理论,对我国小学一年级至大学四年级全日制在校师生,及与之对应的学生家长和所在地区的教育主管部门等进行了调查研究,借助于系统动力学理论,构建校园足球发展系统动力学模型,并利用实际调查数据对模型进行了仿真。结果表明：我国校园足球总体发展动力不强：就系统内环境而言,学生的足球运动需要、可支配运动时间、场地器材及师资力量等系统要素发展不协调,阻碍了校园足球发展;就系统外环境而言,足球的教育价值宣传力度较小、特长生升学通道不畅、足球专项资金监管力度较低等因素,影响校园足球内环境要素的发展,进而影响校园足球的发展。为促进校园足球发展,国家需要大力宣传足球运动的教育价值,完善足球特长生升学通道,加强场地器材建设和师资培训,强化校园足球专项资金的监管力度。     

Multimedia search capabilities of Chinese language search engines

This paper reports results from a study exploring the multimedia search functionality of Chinese language search engines. Web searching in Chinese (Mandarin) is a growing research area and a technical challenge for popular commercial Web search engines. Few studies have been conducted on Chinese language search engines. We investigate two research questions: which Chinese language search engines provide multimedia searching, and what multimedia search functionalities are available in Chinese language Web search engines. Specifically, we examine each Web search engine’s (1) features permitting Chinese language multimedia searches, (2) extent of search personalization and user control of multimedia search variables, and (3) the relationships between Web search engines and their features in the Chinese context. Key findings show that Chinese language Web search engines offer limited multimedia search functionality, and general search engines provide a wider range of features than specialized multimedia search engines. Study results have implications for Chinese Web users, Website designers and Web search engine developers.     

科研项目间接费用补偿的激励作用研究

间接费用的补偿是科研项目经费管理的重要内容。本文从中国间接费用管理实践中存在的问题与现有研究的不足出发,首先分析了间接费用的定义与内涵,提出间接费用在政府科研资助、经费管理体系中的激励作用。其次,在委托代理理论框架下建立了间接费用补偿激励作用的分析模型,并提出影响其激励作用的关键因素。再次,基于国际实践的分析归纳形成两种典型的间接费用补偿模式,并分析其激励作用。最后,基于中国实践提出对科研项目间接费用补偿管理改革的政策建议。     

DNA microarray wet lab simulation brings genomics into the high school curriculum

We have developed a wet lab DNA microarray simulation as part of a complete DNA microarray module for high school students. The wet lab simulation has been field tested with high school students in Illinois and Maryland as well as in workshops with high school teachers from across the nation. Instead of using DNA, our simulation is based on pH indicators, which offer many ideal teaching characteristics. The simulation requires no specialized equipment, is very inexpensive, is very reliable, and takes very little preparation time. Student and teacher assessment data indicate the simulation is popular with both groups, and students show significant learning gains. We include many resources with this publication, including all prelab introductory materials (e.g., a paper microarray activity), the student handouts, teachers notes, and pre- and postassessment tools. We did not test the simulation on other student populations, but based on teacher feedback, the simulation also may fit well in community college and in introductory and nonmajors' college biology curricula.     

经典测量理论与项目反应理论的比较研究

文章通过对经典测量理论和项目反应理论的模型及其假设、主要概念和参数、测量水平等方面进行比较,廓清了两种理论的联系和区别,明确了两种理论的优势和不足,从而为研究者根据测验实践的要求和各个理论的适用条件选择恰当的分析框架提供思路。     

长枞水电大坝的热弹性与渗漏分析

This paper deals with the temperature and displacement fields of the top mid-block of south transition at Long Spruce Generating Station, in the North of Manitoba, Canada. According to the experimental results of Manitoba Hydro in the past two years, the top mid-block is assumed to be a rectangular one that has two supposed temperature distributions at its boundary sides. Then, the temperature fields for the top mid-block are obtained from the analytical solutions by separation of variables. By using the analytical solution of temperature field, the displacement behavior of the top block in various temperature fields is discussed in details. The numerical results are given to show the causes of the leakage between the top mid-block and the dam. Finally, the repair methods for leakage are discussed for practical leaking repair and its engineering applications.     

Youth on the street: Abuse and neglect in the eighties

This paper discusses the findings of a study of runaways and homeless youth who were interviewed on the street the last week of every month on five week nights from late afternoon until 2 a.m. over a period of one year. The data derived from 489 interviews provided some interesting insights. Two distinct groups emerged from the analysis, generating a tentative hypothesis that the true "runners" tend to leave their homes with the intention of not returning and thus their runs are extended; the second group, designated "in and outers," use the run as a temporary coping mechanism. Their runs tend to be impulsive and of short duration. The study found that runaways (in particular the runners) are at great risk of being drawn into illegal activities. Major factors affecting this risk are distance from home and length of time on the run. A significant proportion of the youth interviewed had run from substitute care arrangements, and a disturbing implication emerging from the research is that adolescents in our society suffer from systemic abuse and neglect. One outcome of this piece of research was the opening of a safe house for early runners in January 1987. The operation of the house includes careful compilation of data to further advance understanding of the runaway population and its needs.     

Resilience in child maltreatment victims: a conceptual exploration

While many child maltreatment victims suffer serious negative emotional sequelae, others do surprisingly well. Resilience in children is a relative concept which can change over time and is affected by environment and genetics. Resilience is fostered by protective factors which ameliorate or alter a child's response to the hazards of maltreatment that usually predispose to maladaptive outcome. Personal characteristics or skills that may foster resilience include (1) rapid responsivity to danger; (2) precocious maturity; (3) dissociation of affect; (4) information seeking; (5) formation and utilization of relationships for survival; (6) positive projective anticipation; (7) decisive risk taking; (8) the conviction of being loved; (9) idealization of an aggressor's competence; (10) cognitive restructuring of painful experiences; (11) altruism; and (12) optimism and hope. There are also generic life circumstances, such as having access to good health, educational, and social welfare services, that foster resilience in children regardless of the specific nature of the stressor. Additionally, there may be abuse-specific protective factors in the environment. Examples might include the quick and full acknowledgment of an offender regarding abuse, or timeliness and permanence of legal actions affecting a child's custody. The life stories of three well-known survivors of various forms of child maltreatment illustrate how protective factors contribute to resilience. A caution is noted regarding how personal characteristics developed for survival may become maladaptive if overused and/or not given up when the stressor no longer exists. Characterological problems are most likely to develop when a child's life circumstances fail to change and the environment never becomes secure.