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Search Results: 1 - 10 of 23371 matches for " BAO Lei "
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Dynamic Models of Learning and Education Measurement
Lei Bao
Physics , 2007,
Abstract: Pre-post testing is a commonly used method in physics education community for evaluating students' achievement and or the effectiveness of teaching through a specific period of instruction. A popular method to analyze pre-post testing results is the normalized gain first brought to the physics education community in wide use by R.R. Hake. This paper presents a measurement based probabilistic model of the dynamic process of learning that explains the experimentally observed features of the normalized gain. In Hake's study with thousands of students' pre-post testing results, he observed that on average 48 courses employing "interactive engagement" types of instruction achieved average normalized gains about two standard deviations greater than did 14 courses subjected to traditional instruction. For all courses the average normalized gains had a very low correlation +0.02 with average pretest scores. This feature of the normalized gain has allowed researchers to investigate the effectiveness of instruction using data collected from classes with widely different average pretest scores. However, the question of why the average normalized gain has this feature and to what extent this feature is generally present is not well understood. In addition, there have been debates as to what the normalized gain actually measures, and concerns that it lacks a probability framework that undergirds psychometric methods such as Item Response Theory (IRT). The present model leads to an explanation of the observed features of the normalized gain, connects to other models such as IRT, and shows that the normalized gain does have a probability framework but one different from that emphasized by IRT.
Analyzing Force Concept Inventory with Item Response Theory
Jing Wang,Lei Bao
Physics , 2010, DOI: 10.1119/1.3443565
Abstract: Item Response Theory (IRT) is a popular assessment method used in education measurement, which builds on an assumption of a probability framework connecting students' innate ability and their actual performances on test items. The model transforms students' raw test scores through a nonlinear regression process into a scaled proficiency rating, which can be used to compare results obtained with different test questions. IRT also provides a theoretical approach to address ceiling effect and guessing. We applied IRT to analyze the Force Concept Inventory (FCI). The data was collected from 2802 students taking intro level mechanics courses at The Ohio State University. The data was analyzed with a 3-parameter item response model for multiple choice questions. We describe the procedures of the analysis and discuss the results and the interpretations. The analysis outcomes are compiled to provide a detailed IRT measurement metric of the FCI, which can be easily referenced and used by teachers and researchers for a range of assessment applications.
Model analysis: Representing and assessing the dynamics of student learning
Lei Bao,Edward F. Redish
Physical Review Special Topics. Physics Education Research , 2006,
Abstract: Decades of education research have shown that students can simultaneously possess alternate knowledge frameworks and that the development and use of such knowledge are context dependent. As a result of extensive qualitative research, standardized multiple-choice tests such as Force Concept Inventory and Force-Motion Concept Evaluation tests provide instructors tools to probe their students’ conceptual knowledge of physics. However, many existing quantitative analysis methods often focus on a binary question of whether a student answers a question correctly or not. This greatly limits the capacity of using the standardized multiple-choice tests in assessing students’ alternative knowledge. In addition, the context dependence issue, which suggests that a student may apply the correct knowledge in some situations and revert to use alternative types of knowledge in others, is often treated as random noise in current analyses. In this paper, we present a model analysis, which applies qualitative research to establish a quantitative representation framework. With this method, students’ alternative knowledge and the probabilities for students to use such knowledge in a range of equivalent contexts can be quantitatively assessed. This provides a way to analyze research-based multiple choice questions, which can generate much richer information than what is available from score-based analysis.
Model Analysis: Assessing the dynamics of student learning
Lei Bao,Edward F. Redish
Physics , 2002,
Abstract: In this paper we present a method of modeling and analysis that permits the extraction and quantitative display of detailed information about the effects of instruction on a class's knowledge. The method relies on a congitive model that represents student thinking in terms of mental models. Students frequently fail to recognize relevant conditions that lead to appropriate uses of their models. As a result they can use multiple models inconsistently. Once the most common mental models have been determined by qualitative research, they can be mapping onto a multiple choice test. Model analysis permits the interpretation of such a situation. We illustrate the use of our method by analyzing results from the FCI.
Student Resources in Quantum Mechanics, or Why Students Need Meta-resources
Keith W. Oliver,Lei Bao
Physics , 2002,
Abstract: We are trying to identify resources students are using to reason in quantum mechanics. In this process we realize students must have not only the right resources available but sophisticated for evaluating and controlling their thought processes. We will discuss examples from student interviews to illustrate our point.
Expression QTL Modules as Functional Components Underlying Higher-Order Phenotypes
Lei Bao,Xuefeng Xia,Yan Cui
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0014313
Abstract: Systems genetics studies often involve the mapping of numerous regulatory relations between genetic loci and expression traits. These regulatory relations form a bipartite network consisting of genetic loci and expression phenotypes. Modular network organizations may arise from the pleiotropic and polygenic regulation of gene expression. Here we analyzed the expression QTL (eQTL) networks derived from expression genetic data of yeast and mouse liver and found 65 and 98 modules respectively. Computer simulation result showed that such modules rarely occurred in randomized networks with the same number of nodes and edges and same degree distribution. We also found significant within-module functional coherence. The analysis of genetic overlaps and the evidences from biomedical literature have linked some eQTL modules to physiological phenotypes. Functional coherence within the eQTL modules and genetic overlaps between the modules and physiological phenotypes suggests that eQTL modules may act as functional units underlying the higher-order phenotypes.
Clony color assay coupled with 5FOA negative selection greatly improves yeast three-hybrid library screening efficiency
Yuanzheng He,Lei Bao,Dinggan Liu
Chinese Science Bulletin , 2001, DOI: 10.1007/BF03183275
Abstract: The recently developed yeast three-hybrid system is a powerful tool for analyzing RNA-protein interactionsin vivo. However, large numbers of false positives are frequently met due to bait RNA-independent activation of the reporter gene in the library screening using this system. In this report, we coupled the colony color assay with the 5FOA (5-fluoroorotic acid) negative selection in the library screening, and found that this coupled method effectively eliminated bait RNA-independent false positives and hence greatly improved library screening efficiency. We used this method successfully in isolation of cDNA of an RNA-binding protein that might play important roles in certain cellular process. This improvement will facilitate the use of the yeast three-hybrid system in analyzing RNA-protein interaction.
Clony color assay coupled with 5FOA negative selection greatly improves yeast three-hybrid library screening efficiency

HE Yuanzheng,BAO Lei,LIU Dinggan,

科学通报(英文版) , 2001,
Abstract: The recently developed yeast three-hybrid system is a powerful tool for analyzing RNA-protein interactions in vivo. However, large numbers of false positives are frequently met due to bait RNA-independent activation of the reporter gene in the library screening using this system. In this report, we coupled the colony color assay with the 5FOA (5-fluoroorotic acid) negative selection in the library screening, and found that this coupled method effectively eliminated bait RNA-independent false positives and hence greatly improved library screening efficiency. We used this method successfully in isolation of cDNA of an RNA-binding protein that might play important roles in certain cellular process. This improvement will facilitate the use of the yeast three-hybrid system in analyzing RNA-protein interaction.
Dose-dependent effects of daidzein in regulating bone formation through estrogen receptors and peroxisome proliferator-activated receptor γ
Lei Bao,Shao-fen Zhang
Zhong Xi Yi Jie He Xue Bao , 2011,
Abstract: Objective: To investigate different doses of daidzein (DAI) in regulating bone formation of osteoblasts, and the regulating mechanisms of estrogen receptors (ERs) and peroxisome proliferator-activated receptor γ (PPARγ) in bone formation.Methods: Human fetal osteoblasts (hFOBs) incubated without any treatment were served as controls (control group). The hFOBs were exposed to DAI of 10-9, 10-7 and 10-5 mol/L for 72 h, and to β-estradiol-17-valerate (E2) of 10-8 mol/L as positive control, respectively. Methyl thiazolyl tetrazolium assay was employed to determine the proliferation status of osteoblasts, and 4-nitrophenyl phosphate disodium salt (PNPP) method was employed to determine the activity of alkaline phosphatase (ALP). ER antagonist ICI 182780 (ICI), ERα-selective antagonist methyl-piperidino-pyrazole (MPP) and irreversible PPARγ antagonist GW9662 (GW) were used to block the corresponding receptor, while hFOBs were exposed to E2 or different concentrations of DAI for 48 h. MTT assay and PNPP method were used respectively to determine the proliferation status and ALP activity of osteoblasts cultured in vitro.Results: The osteoblast proliferation rate decreased progressively as the dose of DAI increased. Compared with the controls, the osteblast proliferation rate in the DAI 10-9 mol/L group increased significantly, while DAI 10-5 mol/L group decreased significantly (P<0.05). ALP level decreased progressively as the dose of DAI increased, but there was no significant difference between groups (P>0.05). When ERs were blocked by ICI, proliferation rates in the E2 group and DAI 10-9, 10-7 and 10-5 mol/L groups were 88.16%, 76.30%, 81.18% and 83.19% respectively, which were all significantly lower than before (P < 0.05). After ERα was blocked by MPP alone, proliferation rates in E2 group and DAI 10-9, 10-7 and 10-5 mol/L groups were 69.78%, 63.31%, 70.71% and 78.43%, respectively, which were also significantly lower than before (P<0.05). ALP level in the DAI 10-9 mol/L group decreased significantly when ERα was blocked alone. When PPARγ inhibitor GW was added to the culture system, proliferation rates in E2 group and DAI 10-9, 10-7 and 10-5 mol/L groups were 103.14%, 96.99%, 112.88% and 122.22%, respectively. Compared with before, proliferation rates in DAI 10-7 and 10-5 mol/L groups increased significantly (P<0.05), and ALP level increased significantly (P<0.05) in the DAI 10-5mol/L group.Conclusion: DAI shows a biphasic effect on osteoporosis, whereby the effect is dose-dependent; a low-dose DAI stimulates proliferation of osteoblasts, while a high-dos
Monge-Ampere equation on exterior domains
Jiguang Bao,Haigang Li,Lei Zhang
Mathematics , 2013,
Abstract: We consider the Monge-Amp\`ere equation $\det(D^2u)=f$ where $f$ is a positive function in $\mathbb R^n$ and $f=1+O(|x|^{-\beta})$ for some $\beta>2$ at infinity. If the equation is globally defined on $\mathbb R^n$ we classify the asymptotic behavior of solutions at infinity. If the equation is defined outside a convex bounded set we solve the corresponding exterior Dirichlet problem. Finally we prove for $n\ge 3$ the existence of global solutions with prescribed asymptotic behavior at infinity. The assumption $\beta>2$ is sharp for all the results in this article.
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