青藏古植被的演变与青藏高原的隆起

 西藏北部，在早石炭世晚期位于欧亚古陆的南缘，其植物群与当时印度次大     陆的不同。在晚二叠世，藏北属华夏植物区(即大羽羊齿植物区)；印度河-雅鲁     藏布江大断裂带以南的地区出现舌羊齿植物群，  因而属冈瓦纳古陆的一部分。     到晚三叠世藏北植物群的面貌与我国西南同时代的植物群相似，与印度的则迥     然不同，显示藏北晚三叠世的植物群与南半球植物群也没有直接联系。  柴达木     侏罗纪植物群和拉萨附近早白垩世植物群与北半球的植物群有密切的关系。日     喀则晚白垩世植物群和阿里早始新世植物群也是如此。他们与印度德干玄武岩     夹层中出现的古新世植物群和印度北部始新世植物群也没有联系。  当时，西藏     的北部和南部属于两个不同的古陆，欧亚古陆和冈瓦纳古陆。  两者之间应有一     个很宽阔的特提斯海。因而，青藏的植物化石强有力地支持了大陆漂移的观点，     印度地块在晚侏罗世—白垩纪时是由非洲东南隅分离向北漂移，到始新世才与     亚洲连接，成为现在的南亚次大陆。  欧亚大陆与印度地块的接合线或许就是印     度河－雅鲁藏布江大断裂带。     　　从晚石炭世到早始新世的植物群的性质上看，藏北地势多半低洼。     中新世时，西藏中部和北部的植被是以落叶阔叶林为主，虽然某些地区有一     些常绿树存在，反映在中新世以前西藏中部和北部的地面已经上升到一定的程     度。在上新世时，藏北的常绿阔叶林逐渐减缩。柴达木盆地的植被转变成落叶     阔叶林－针叶林，以后转变成草原和半荒漠或荒漠，显示西藏和青海的地面进一     步抬升。     　　到晚上新世，藏北和青海的植被再行演变。然而，喜马拉雅地区的植被仍然     具有常绿栎林和雪松林。可能那时喜马拉雅山不像现在那么高。印度洋的季风     可以吹过喜马拉雅山，没有高山的阻碍。     　　第四纪是青藏山系和青藏地面上升最剧烈的时期。此时藏北已无常绿阔叶     树的存在。  到第四纪后期西藏大部分地区的植被逐渐演变为高寒荒漠。  最后，    青藏高原变成现在的情况。     

Promoting social and academic competence in the classroom: An intervention study examining the contribution of the Responsive Classroom approach

This exploratory study examined the contribution of the RC Approach over a two‐year period. The RC Approach integrates social and academic learning in order to produce classroom environments that are conducive to learning by integrating social and academic learning. Two questions are addressed. First, how does teachers' use of RC practices contribute to children's academic and social growth? Second, how is the relation between teachers' use of RC practices and children's academic and social growth moderated by the presence of environmental adversity in the home? Participants included 62 teachers and 157 children at six schools. Findings showed that teachers' use of RC practices was associated with students' improved reading achievement, greater closeness between teachers and children, better pro‐social skills, more assertiveness, and less fearfulness, even after controlling for family risk and children's previous years' performance. Family risk did not moderate the relation between RC practices and children's performance. These findings suggest to the positive contribution of the RC Approach in relation to children's gains over a one‐year period. © 2007 Wiley Periodicals, Inc. Psychol Schs 44: 397–413, 2007.     

Parental Co‐Construction of 5‐ to 13‐Year‐Olds' Global Self‐Esteem Through Reminiscing About Past Events

The current study explored parental processes associated with children's global self‐esteem development. Eighty 5‐ to 13‐year‐olds and one of their parents provided qualitative and quantitative data through questionnaires, open‐ended questions, and a laboratory‐based reminiscing task. Parents who included more explanations of emotions when writing about the lowest points in their lives were more likely to discuss explanations of emotions experienced in negative past events with their child, which was associated with child attachment security. Attachment was associated with concurrent self‐esteem, which predicted relative increases in self‐esteem 16 months later, on average. Finally, parent support also predicted residual increases in self‐esteem. Findings extend prior research by including younger ages and uncovering a process by which two theoretically relevant parenting behaviors impact self‐esteem development.     

Elementary school–wide implementation of a blended learning program for reading intervention

The authors examined the implementation of a blended learning program for literacy instruction across kindergarten through Grade 5 in a Title I urban elementary school, including a population of students (18%) who are English learners. Student progress in the online component of the blended learning program was a significant predictor of growth in reading performance on a standardized reading assessment (Group Reading Assessment and Diagnostic Evaluation, Pearson Assessment, Boulder, CO) when controlling for student grade level, initial student skill level, and English learner status; however, students in kindergarten through Grade 2 showed more substantial gains than students in later grades. These results suggest there is a benefit of a blended learning approach to literacy instruction for a diverse cross-section of students, particularly when beginning instruction in the early grades.     

Effects of the inquiry-based mobile learning model on the cognitive load and learning achievement of students

The advancement of mobile device and wireless communication technologies is having a great influence on the design concept of learning activities. In this study, we attempt to integrate field study into the inquiry-based mobile learning model; moreover, a mobile learning environment that allows students to access both physical and virtual resources is developed accordingly. During the in-field learning activity, the mobile learning system is able to present the learning tasks, guide the students to visit the real-world learning targets for exploration, and provide them with supplementary materials via the mobile devices. The aim of this research focuses on the effects of this mobile learning model on students' cognitive load and learning achievements. The 51 sixth graders who participated in this research were assigned to an experimental and a control group. From the pre and posttests as well as the cognitive load questionnaire, it was found that the students who learned with the inquiry-based mobile learning approach had better learning achievement and less cognitive load than those who learned with the traditional approach. Therefore, it is concluded that the mobile learning model has positive effects on elementary students in local culture learning.     

Developing digital portfolios: investigating how digital portfolios can facilitate pupil talk about learning

The Digital Portfolio Project at Newcastle University aimed over one year (2002/2003) to support teachers in producing, storing and accessing assessment portfolios of learner’s work using information and communications technology (ICT). This paper draws on evidence of pupil views collected as part of 14 teacher‐led case studies. The teachers all approached the task of developing digital portfolios in different ways and the variety of end products was large; however, the common result was the value placed on using the portfolio as a tool for reflection and celebration of children’s learning. As part of the data collection teachers were encouraged to gather pupil views about the digital portfolio learning process. These comments provide an interesting and surprisingly analytical perspective of the research and learning process not commonly considered in the academic community. This paper documents the pupils’ views and uses them to review the strength of the digital portfolio process and the benefits of using it in the primary classroom.     

Why might relative fit indices differ between estimators?

Previous research indicates that relative fit indices in structural equation modeling may vary across estimation methods. Sugawara and MacCallum (1993) explained that the discrepancy arises from difference in the function values for the null model with no further derivation given. In this study, we derive explicit solutions for parameters of the null model. The null model specifies the variances of the observed variables as model parameters and fixes all the covariances to be zero. Three methods of estimation are considered: the maximum likelihood (ML) method, the ordinary least squares (OLS) method, and the generalized least squares (GLS) method. Results indicate that ML and LS yield an identical estimator, which is different from GLS. Function values and associated chi‐square statistics of the null model vary across estimation methods. Consequently, relative fit indices using the null model as the reference point in computation may yield different results depending on the estimation method chosen. An illustration example is given and implications of this study are discussed.     

An innovative concept map approach for improving students' learning performance with an instant feedback mechanism

Concept maps have been widely employed for helping students organise their knowledge as well as evaluating their knowledge structures in a wide range of subject matters. Although researchers have recognised concept maps as being an important educational tool, past experiences have also revealed the difficulty of evaluating the correctness of a concept map. It usually takes days or weeks for teachers to manually evaluate the concept maps developed by students; consequently, the students cannot receive timely feedback from the teachers, which not only affects their learning schedules, but also significantly influences the students' learning achievements. In this paper, a computer‐based concept map‐oriented learning strategy with real‐time assessment and feedback is proposed in order to cope with the problems mentioned above. Our approach provides immediate evaluation of concept maps and gives also real‐time feedback to the students. An experiment has been conducted to evaluate the effectiveness of this new strategy in comparison with the conventional computer‐based concept map approach. It is found that our innovative approach can be significantly beneficial to promote learning achievements as well as the learning attitudes of students.