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Search Results: 1 - 10 of 23728 matches for " Dandan Zheng "
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Empirical Study and Model of Users Acceptance for Mobile Commerce in China
Hua Zheng,Ying Li,Dandan Jiang
International Journal of Computer Science Issues , 2012,
Abstract: Merchants urgently need to investigate consumers willingness to accept mobile commerce and what factors influence their acceptance since the spring up of mobile commerce. By means of surveying Chinese consumers with questionnaire, this paper take consumer as research object to analyze their attitude toward using and influence factors about mobile commerce based on the user acceptance theory. The research result shows that consumers attitude toward using is influenced significantly by perceived usefulness, perceived cost, perceived entertainment and its own development of mobile commerce, especially the factor of perceived usefulness. Although the trial ability of service doesnt influence attitude toward using directly, it has indirect effect on attitude toward using through perceived usefulness.
The Population Age Structure, the Real Effective Exchange Rate and the Current Account Balance—Empirical Analysis Based on the Data of Chinese Provincial Panel  [PDF]
Dandan Zhou
American Journal of Industrial and Business Management (AJIBM) , 2018, DOI: 10.4236/ajibm.2018.81005
Abstract: This paper takes the panel data of 29 provinces, municipalities and autonomous regions in China as samples from 1994 to 2015, using dynamic panel GMM to analyze the relationship between China’s population age structure, the real effective exchange rate and current account balance. System generalized method of moments and robustness test show that the adjustment of China’s current projects has obvious inertial characteristics; the change of population age structure has significant negative influence on the current account balance, the impact of youth dependency ratio on the current account is not significant, the elderly dependency ratio has a significant negative impact on current account; the effect of the real effective exchange rate on current account is not significant, the “Theory of Exchange Rate Manipulation in the Chinese Government” is not valid and untenable. The conclusion of this paper shows that the change of population age structure is an important reason for the long-term surplus of China’s current account.
The Influence of Peer Relationship on Middle School Students’ Education
—CEPS Data Based on 2013-2014 Baseline
 [PDF]

Dandan Li
Open Journal of Social Sciences (JSS) , 2018, DOI: 10.4236/jss.2018.64007
Abstract:
This paper uses data from the China Education Tracking Survey (CEPS) to explore the impact of peer relationships on the academic performance of students in the ninth grade. First, according to the number of migrants in the area, the sample is divided into three groups, namely, Shanghai, a region with a large number of floating population and a national core sample formed in other parts of the country. Then, the local students in each sample group are grouped with the foreign students, and the impact of peer relationship on their academic performance is analyzed respectively by regression analysis. Then the differences among the groups are compared. Finally, the sample is limited to the sample of students in the rural household registration system. Parent-child relationship is added to control the influence of the family environment and a robustness test is conducted. Through these empirical studies, we find: 1) There are differences in the impact of peer relationships on academic performance in different regions. In the Shanghai sample, there is no significant correlation between peer relationship and academic achievement; in regions with a large number of floating population, the quality of peer impact on academic performance is greater than that of national core sample with fewer floating population. 2) The impact of peer relations on students in different regions in China and foreign countries is different. In areas with a large number of floating population, peer relationships significantly affect the academic performance of overseas students. In the national core sample, peer relationships significantly affect the academic performance of local students, with no significant impact on foreign students. 3) There are differences in the impact of peer relations on Chinese and mathematics. Among them, the least impact on the language proficiency. 4) There is a significant positive correlation between student evaluation of peer relationships and academic achievement. The impact of communication frequency on academic performance may be poor.
Prediction of antigenic epitopes on protein surfaces by consensus scoring
Shide Liang, Dandan Zheng, Chi Zhang, Martin Zacharias
BMC Bioinformatics , 2009, DOI: 10.1186/1471-2105-10-302
Abstract: We present a new antigen Epitope Prediction method, which uses ConsEnsus Scoring (EPCES) from six different scoring functions - residue epitope propensity, conservation score, side-chain energy score, contact number, surface planarity score, and secondary structure composition. Applied to unbounded antigen structures from an independent test set, EPCES was able to predict antigenic eptitopes with 47.8% sensitivity, 69.5% specificity and an AUC value of 0.632. The performance of the method is statistically similar to other published methods. The AUC value of EPCES is slightly higher compared to the best results of existing algorithms by about 0.034.Our work shows consensus scoring of multiple features has a better performance than any single term. The successful prediction is also due to the new score of residue epitope propensity based on atomic solvent accessibility.Realistic prediction of protein surface regions that are preferentially recognized by antibodies (antigenic epitopes) can help in the design of vaccine components and immuno-diagnostic reagents. Antigenic epitopes are classified as continuous or discontinues epitopes. If the residues involved in an epitope are contiguous in the polypeptide chain, this epitope is called a continuous epitope or a linear epitope. On the other hand, a discontinuous or non-linear epitope is composed of residues that are not necessarily continuous in the polypeptide sequence but have spatial proximity on the surface of a protein structure. A significant fraction of epitopes are discontinuous in the sense that antibody binding is not fully determined by a linear peptide segment but also influenced by adjacent surface regions [1].However, the majority of available epitope prediction methods focus on continuous epitopes due to the convenience of the investigation in which the amino acid sequence of a protein is taken as the input. Such prediction methods are based upon the amino acid properties including hydrophilicity [2,3], so
Production Test on Facultative Anaerobic-AB Process In Treating Slaughterhouse Wastewater and Its Microbiological Characteristics
兼氧-AB工艺处理屠宰废水工程性试验及其微生物学特性研究

Zheng Dandan,
郑丹丹
,陈玉谷,万秀林

环境科学 , 1993,
Abstract: 废水处理试运行期间,兼性厌氧调节池负荷率平均为0.50kgCOD_(Cr)/(m~3·d),COD_(Cr)去除率31.15%;A级污泥负荷B_(TS)平均为4.78kg BOD_5/(kg MLSS·d),COD_(cr)去除率53.37%;B级B_(TS) 0.73kg BOD_5/(kg MLSS·d),COD_(Cr)占除率54.70%。处理出水几项主要污染指标达到《GB8978—88》污水综合排放标准,其中COD_(Cr)103.1mg/L(去除88.77%),BOD_5 32.0mg/L(去除94.47%),SS 36.1mg/L(去除89.64%),色度26倍(去除80.60%),pH7.72。投入正式运行后,出水水质稳定,相对标准差0.48。在兼性厌氧调节池生物膜中,存在着厌氧发酵微生物区系;好氧处理阶段的A级以细菌为主,B级以原生动物和菌胶团为主,原生动物占优势。
Fabrication and magnetic properties of granular Co/porous InP nanocomposite materials
Zhou Tao,Cheng Dandan,Zheng Maojun,Ma Li
Nanoscale Research Letters , 2011,
Abstract: A novel Co/InP magnetic semiconductor nanocomposite was fabricated by electrodeposition magnetic Co nanoparticles into n-type porous InP templates in ethanol solution of cobalt chloride. The content or particle size of Co particles embedded in porous InP increased with increasing deposition time. Co particles had uniform distribution over pore sidewall surface of InP template, which was different from that of ceramic template and may open up new branch of fabrication of nanocomposites. The magnetism of such Co/InP nanocomposites can be gradually tuned from diamagnetism to ferromagnetism by increasing the deposition time of Co. Magnetic anisotropy of this Co/InP nanocomposite with magnetization easy axis along the axis of InP square channel was well realized by the competition between shape anisotropy and magnetocrystalline anisotropy. Such Co/InP nanocomposites with adjustable magnetism may have potential applications in future in the field of spin electronics. PACS: 61.46. +w · 72.80.Tm · 81.05.Rm · 75.75. +a · 82.45.Aa
Vitreous Incarceration in Patients Undergoing Second 20-Gauge Pars Plana Vitrectomy for Recurrent Retinal Detachment
Yongxin Zheng,Haotian Lin,Wen Liu,Dandan Wang
ISRN Ophthalmology , 2011, DOI: 10.5402/2011/456191
Abstract:
Conformational B-Cell Epitope Prediction on Antigen Protein Structures: A Review of Current Algorithms and Comparison with Common Binding Site Prediction Methods
Bo Yao, Dandan Zheng, Shide Liang, Chi Zhang
PLOS ONE , 2013, DOI: 10.1371/journal.pone.0062249
Abstract: Accurate prediction of B-cell antigenic epitopes is important for immunologic research and medical applications, but compared with other bioinformatic problems, antigenic epitope prediction is more challenging because of the extreme variability of antigenic epitopes, where the paratope on the antibody binds specifically to a given epitope with high precision. In spite of the continuing efforts in the past decade, the problem remains unsolved and therefore still attracts a lot of attention from bioinformaticists. Recently, several discontinuous epitope prediction servers became available, and it is intriguing to review all existing methods and evaluate their performances on the same benchmark. In addition, these methods are also compared against common binding site prediction algorithms, since they have been frequently used as substitutes in the absence of good epitope prediction methods.
Corrections to LRT on Large Dimensional Covariance Matrix by RMT
Zhidong Bai,Dandan Jiang,Jian-feng Yao,Shurong Zheng
Mathematics , 2009, DOI: 10.1214/09-AOS694
Abstract: In this paper, we give an explanation to the failure of two likelihood ratio procedures for testing about covariance matrices from Gaussian populations when the dimension is large compared to the sample size. Next, using recent central limit theorems for linear spectral statistics of sample covariance matrices and of random F-matrices, we propose necessary corrections for these LR tests to cope with high-dimensional effects. The asymptotic distributions of these corrected tests under the null are given. Simulations demonstrate that the corrected LR tests yield a realized size close to nominal level for both moderate p (around 20) and high dimension, while the traditional LR tests with chi-square approximation fails. Another contribution from the paper is that for testing the equality between two covariance matrices, the proposed correction applies equally for non-Gaussian populations yielding a valid pseudo-likelihood ratio test.
Assessing the Therapeutic Effect of 630 nm Light-Emitting Diodes Irradiation on the Recovery of Exercise-Induced Hand Muscle Fatigue with Surface Electromyogram
Dandan Yang,Xiaoying Wu,Wensheng Hou,Xiaolin Zheng,Jun Zheng,Yingtao Jiang
International Journal of Photoenergy , 2012, DOI: 10.1155/2012/652040
Abstract: This paper aims to investigate the effect of light emitting diode therapy (LEDT) on exercise-induced hand muscle fatigue by measuring the surface electromyography (sEMG) of flexor digitorum superficialis. Ten healthy volunteers were randomly placed in the equal sized LEDT group and control group. All subjects performed a sustained fatiguing isometric contraction with the combination of four fingertips except thumb at 30% of maximal voluntary contraction (MVC) until exhaustion. The active LEDT or an identical passive rest therapy was then applied to flexor digitorum superficialis. Each subject was required to perform a re-fatigue task immediately after therapy which was the same as the pre-fatigue task. Average rectified value (ARV) and fractal dimension (FD) of sEMG were calculated. ARV and FD were significantly different between active LEDT and passive rest groups at 20%–50%, 70%–80%, and 100% of normalized contraction time (P<0.05). Compared to passive rest, active LEDT induced significantly smaller increase in ARV values and decrease in FD values, which shows that LEDT is effective on the recovery of muscle fatigue. Our preliminary results also suggest that ARV and FD are potential replacements of biochemical markers to assess the effects of LEDT on muscle fatigue.
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