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Comparative study of electrical characteristics for n-type 4H–SiC planar and trench MOS capacitors annealed in ambient NO

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Chinese Physics B 2017年第10期26卷 404-410页

作者：申占伟张峰 sima Dimitrijev 韩吉胜闫果果温正欣赵万顺王雷刘兴昉孙国胜曾一平 Key Laboratory of Semiconductor Material Sciences Institute of Semiconductors University of Chinese Academy of Sciences College of Materials Science and Opto-Electronic Technology University of Chinese Academy of Sciences Queensland Micro- and Nano-technology Center Griffith University

The interface properties and electrical characteristics of the n-type 4H-SiC planar and trench metal-oxide-semiconductor （MOS） capacitors are investigated by measuring the capacitance voltage and current voltage. The flat-band voltage and interface state density are evaluated by the quasi-static method. It is not effective on further improving the interface properties annealing at 1250 ℃ in NO ambient for above 1 h due to the increasing interface shallow and fast states. These shallow states reduce the effective positive fixed charge density in the oxide. For the vertical MOS capacitors on the （1120） and （1100） faces, the interface state density can be reduced by approximately one order of magnitude, in comparison to the result of the planar MOS capacitors on the （0001） face under the same NO annealing condition. In addition, it is found that Fowler-Nordheim tunneling current occurs at an oxide electric field of 7 MV/cm for the planar MOS device. However, Poole-Frenkel conduction current occurs at a lower electric field of 4 MV/cm for the trench MOS capacitor. This is due to the local field crowded at the trench corner severely causing the electrons to be early captured at or emitted from the SiO2/SiC interface. These results provide a reference for an in-depth understanding of the mobility-limiting factors and long term reliability of the trench and planar SiO2/SiC interfaces.

关键词： 4H-SiC metal-oxide-semiconductor capacitors trench interface states nitric oxide annealing

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埃塞俄比亚政府支出对国内经济增长的作用

埃塞俄比亚政府支出对国内经济增长的作用

作者： Melat sima（美佳）首都经济贸易大学

学位级别：硕士

长期以来,市政开支或政府对国家的经济介入所起到的作用一直是人们研究的焦点,并且未得出一致结论。本文以埃塞俄比亚为例,通过调查埃塞俄比亚33年来的政府支出和国内生产总值数据,研究了其财政支出对该国经济增长的影响和作用。基于财... 详细信息

长期以来,市政开支或政府对国家的经济介入所起到的作用一直是人们研究的焦点,并且未得出一致结论。本文以埃塞俄比亚为例,通过调查埃塞俄比亚33年来的政府支出和国内生产总值数据,研究了其财政支出对该国经济增长的影响和作用。基于财政支出的不同分类,分别建立了两种经济模型。第一种模型是基于政府用于国外援助等资本支出和经常性开支(部门支出则作为次要考虑),采用单位根检验法验证了变量的平稳性,检验结果表明多数变量趋势的存在,另外采用了协整检验法验证出了在两组变量中至少存在一个协整方程。另外,还采用了基于最小二乘法的多元回归分析方法。测试了序列相关性和异方差性后,解释了回归系数。通过T检验确认了显著变量,同时方差齐性检验的结果表明两组变量对国内生产总值都具有显著的集体影响。最后回归系数解释指出在促进经济增长方面,经常性支出比资本支出具有更为积极的作用,例如经常性支出和资本支出都增加2.72%时,那么经常性支出将使log(GDP)值提升0.54,而资本支出仅增加0.37个log(GDP)。第二种模型对部门支出进行了调查。其中卫生部的支出最为有影响力。卫生部支出的两倍将能导致该国国内生产总值1.62%的涨幅。而教育部的支出对国内生产总值的影响力相对较弱。这说明在过去30年内,政府对教育的投入并未导致损失。以上结果表明埃塞俄比亚政府支出对其本国的经济增长具有重要作用,因此该政府在未来应继续实行相关支出方。

关键词：政府支出国内生产总值多元回归最小二乘法

Clustering Color Image Segmentation Based on Maximum Entropy

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Clustering Color Image Segmentation Based on Maximum Entropy

国家培训政策对坦桑尼亚公立教师培训学院校长领导、行政和管理效率的影响

2012年计算机应用与系统建模国际会议

作者： sima Haifeng Liu Lanlan School of Computer Science and Technology Henan Polytechnic University School of Computer Science and Technology Beijing Institute of Technology School of Emergence Management Henan Polytechnic University

Maximum entropy is meaningful for representing pixels spatial distribution in the image. This paper proposed a new clustering segmentation approach for color image according to the maximum entropy. Firstly, quantize the HSV color space to equal intervals. The probability distribution of pixels in the quantized space can be seen as a random process. Select a slide interval on the histogram to estimate the classes based on the maximum entropy in the color space. Then observed class number and the initial cluster center. Segmented pixels in to regions by clustering and used spatial filtering to eliminate meaningless regional and holes. The experiment results has shown that this algorithm achieved a good segmentation.

关键词： Color image Segmentation Maximum entropy theory K-means clustering

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国家培训政策对坦桑尼亚公立教师培训学院校长领导、行政和管理效...

作者： Juma Athumani sima 华东师范大学

学位级别：硕士

本研究就国家培训政策对坦桑尼亚公立教师培训学院校长在领导、行政和管理效率的重要影响进行了考察。鉴于教育改革要基于标准,教师培训学院领导力的办学目标是创造有效的领导力、行政能力和管理能力,力求学生的优秀学业表现。本研究的... 详细信息

本研究就国家培训政策对坦桑尼亚公立教师培训学院校长在领导、行政和管理效率的重要影响进行了考察。鉴于教育改革要基于标准,教师培训学院领导力的办学目标是创造有效的领导力、行政能力和管理能力,力求学生的优秀学业表现。本研究的文献回顾揭示了诸多重要因素,例如培训政策、学校领导取向、校长专业发展框架、学校管理成果、政策对校长领导力的影响、相关概念和理论框架以及与以往著述的知识差距。学校领导能力是目前一大研究热点,许多学者尝试着研究校长恰当的培训和专业发展,也试图分析相应领导能力对学生学业表现所起到的重要作用。本研究采用了混合型的研究方法,以适于对本研究一手资料来源的校长、副校长、教师培训学院老师以及教育、科学和技术部的高级官员和政策制定者通过开放式和封闭式问卷结合半结构化访谈收集数据。数据分析采取描述型方法,使用了Python、Stata、Excel等软件,并对受访者的意见进行解释分析。同时,本研究采用结构方程模型(SEM)对培训政策与培训学院校长领导、行政和管理效率之间的关系进行了分析,以探寻可行的改善方法,并提出相关建议。研究结果证明,现行的校长招聘、选拔、任用与不连续的专业发展培训这样的集中管理方式,无法满足当前不断变化的学校教师教育和教师培训管理的要求。本研究表明,建立国家级校长培训机构、培训中心,或者与大学建立合作伙伴关系,可以最大限度地提高行政效率、领导力和管理效率,也能解决问题,改善目前的状况。这些高等教育机构可以为校长和学校领导提供高级学历学位证书,也能组织界限分明、结构良好的职业发展培训项目。根据本研究的主要发现,我们认为:政府、教育机构、教师培训学院和各级学校应建立结构合理的培训政策,重视对领导者倡导在行政管理、领导力诸方面进行变革、完善和发展能力的培训,以解决坦桑尼亚教师培训学院中普遍存在的问题和挑战。国家培训政策的出台,将会影响校长职前以及在职专业发展的管理架构。以明确的标准,对教师培训学院的指导老师、教师或者有志于将担任教师培训学院校长作为自己职业生涯目标的任何个人的招聘予以制度化,将提升坦桑尼亚教师培训学院校长职位的专业化水平。

关键词：影响国家培训政策效率领导力教师培训学院校长

Singular Hybrid Boundary Node Method for Solving Poisson Equation

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Chinese Quarterly Journal of Mathematics 2008年第2期23卷 284-291页

作者： sima Yu-zhou ZHU Hong-ping MIAO Yu School of Civil Engineering and Mechanics Huazhong University of Science and Technology Wuhan430074 China

As a boundary-type meshless method, the singular hybrid boundary node method（SHBNM） is based on the modified variational principle and the moving least square（MLS） approximation, so it has the advantages of both boundary element method（BEM） and meshless method. In this paper, the dual reciprocity method（DRM） is combined with SHBNM to solve Poisson equation in which the solution is divided into particular solution and general solution. The general solution is achieved by means of SHBNM, and the particular solution is approximated by using the radial basis function（RBF）. Only randomly distributed nodes on the bounding surface of the domain are required and it doesn＇t need extra equations to compute internal parameters in the domain. The postprocess is very simple. Numerical examples for the solution of Poisson equation show that high convergence rates and high accuracy with a small node number are achievable.

关键词： singular hybrid boundary node method dual reciprocity method Poisson equation

Fatty liver index vs waist circumference for predicting non-alcoholic fatty liver disease

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World Journal of Gastroenterology 2016年第10期22卷 3023-3030页

作者： Nima Motamed Masoudreza Sohrabi Hossein Ajdarkosh Gholamreza Hemmasi Mansooreh Maadi Fatemeh sima Sayeedian Reza Pirzad Khadijeh Abedi Sivil Aghapour Mojtaba Fallahnezhad Farhad Zamani Department of Social Medicine Zanjan University of Medical Sciences Zanjan 45154 Iran Gastrointestinal and Liver Disease Research Center Iran University of Medical Sciences Tehran 159347 Iran Department of Endocrinology Sari University of Medical Sciences Tehran 159347 Iran Razi Science Researchers Institute Karaj 31976 Iran

AIM: To determine the discriminatory performance of fatty liver index (FLI) for non-alcoholic fatty liver disease (NAFLD).METHODS: The data of 5052 subjects aged over 18 years were analyzed. FLI was calculated from body mass index, waist circumference (WC), triglyceride, and gamma glutamyl transferase data. Logistic regression analysis was conducted to determine the association between FLI and NAFLD. The discriminatory performance of FLI in the diagnosis of NAFLD was evaluated by receiver operating characteristic analysis. Area under the curves (AUCs) and related confidence intervals were estimated. Optimal cutoff points of FLI in the diagnosis of NAFLD were determined based on the maximum values of Youden’s ***: The mean age of men and women in the study population were 44.8 ± 16.8 and 43.78 ± 15.43, respectively (P = 0.0216). The prevalence of NAFLD was 40.1% in men and 44.2% in women (P < 0.0017). FLI was strongly associated with NAFLD, so that even a one unit increase in FLI increased the chance of developing NAFLD by 5.8% (OR = 1.058, 95%CI: 1.054-1.063, P < 0.0001). Although FLI showed good performance in the diagnosis of NAFLD (AUC = 0.8656 (95%CI: 0.8548-0.8764), there was no significant difference with regards to WC (AUC = 0.8533, 95%CI: 0.8419-0.8646). The performance of FLI was not significantly different between men (AUC = 0.8648, 95%CI: 0.8505-0.8791) and women (AUC = 0.8682, 95%CI: 0.8513-0.8851). The highest performance with regards to age was related to the 18-39 age group (AUC = 0.8930, 95%CI: 0.8766-0.9093). The optimal cutoff points of FLI were 46.9 in men (sensitivity = 0.8242, specificity = 0.7687, Youden’s index = 0.5929) and 53.8 in women (sensitivity = 0.8233, specificity = 0.7655, Youden’s index = 0.5888).CONCLUSION: Although FLI had acceptable discriminatory power in the diagnosis of NAFLD, WC was a simpler and more accessible index with a similar performance.

关键词： Non-alcoholic fatty liver disease Fatty liver index Waist circumference Body mass index Optimal cutoff points Discriminatory performance

Polymorphism identification of carotenoid binding protein gene transcription in the silkworm, <i>Bombyx mori</i>

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Advances in Bioscience and Biotechnology 2012年第2期3卷 107-114页

作者： Yanshan Niu Feifei Long Yanghu sima Shiqing Xu National Engineering Laboratory for Modern Silk Department of Applied Biology Medical College Soochow University Suzhou China

Carotenoids play important and diverse roles in insects and their uptake and transport rely on carotenoid binding protein (CBP). The study excavated a cluster of CBP-like transcripts, including full CBP from all of the six yellow cocoon Bombyx strains investigated. Sequencing of 54 cDNA clones revealed 17 different types of transcripts which derived from alternative splicing of CBP gene locus. Five of the novel transcripts were similar with spatial and temporal distribution patterns to CBP, but their expression levels were relatively lower. The author disclosed two more novel alternative spliced transcripts with different transcription start sites from CBP in the 5’ UTRs as well as 11 SNP sites neighboring intron 1 after amplification and sequencing. qRT-PCR analysis gave evidence that relatively more mRNA was transcribed from A-type CBP gene than that from B-type in tissues like silk gland and midgut. Sequences of A- and B-type CBP genes were different in length of domains neighboring the 5’ UTR, thus their mRNA varied both in quantity and transcript types. The SNPs surrounding intron 1 can serve as stable markers to distinguish transcripts from the two isoforms, and they can be used for molecular marker assisted selection.

关键词： Carotenoid-Binding Protein Gene Alternative Splicing Transcripts Single Nucleotide Polymorphism Bombyx mori

Vascular endothelial growth factor promotes peripheral nerve regeneration after sciatic nerve transection in rat

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Chinese Journal of Traumatology 2013年第6期16卷 323-329页

作者： Rahim Mohammadi sima Ahsan Masoume Masoumi Keyvan Amini Department of Clinical Sciences Faculty of VeterinaryMedicine Urmia University Urmia 571531177 Iran Department of Veterinary Pathology Western Collegeof Veterinary Medicine University of SaskatchewanSaskatoon Saskatchewan S7N 5B4 Canada

Objective：To evaluate the local effect of vascular endothelial growth factor （VEGF） on transected sciatic nerve ***：Sixty male white Wistar rats were divided into four experimental groups randomly （n=15）.In transected group the left sciatic nerve was transected and the stump was fixed to adjacent *** treatment group the defect was bridged using a silicone graft filled with 10μL *** silicone group the graft was filled with phosphate-buffered *** sham-operated group the sciatic nerve was exposed and *** group was subdivided into three subgroups with five animals in each and nerve fibers were studied 4,8 and 12 weeks after ***：Behavioral test,functional study of sciatic nerve,gastrocnemius muscle mass and morphometric indices confirmed a faster recovery of regenerated axons in VEGF group than in silicone group （P〈0.05）.In immunohistochemical assessment,reactions to S-100 in VEGF group were more positive than that in silicone ***：Local administration of VEGF will improve functional recovery and morphometric indices of sciatic nerve.

关键词： Peripheral nerves Nerve regeneration Sciatic nerve Vascular endothelial growth factor

p16 promoter hypermethylation:A useful serum marker for early detection of gastric cancer

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World Journal of Gastroenterology 2008年第13期14卷 2055-2060页

作者： Mohammad Reza Abbaszadegan Omeed Moaven Hamid Reza sima Kamran Ghafarzadegan Azadeh A'rabi Mohammad Naser Forghani Hamid Reza Raziee Ali Mashhadinejad Mostafa Jafarzadeh Ehsan Esmaili-Shandiz Ezzat Dadkhah Division of Human Genetics Immunology Research Center Avicenna Research Institute Mashhad University of Medical Sciences Mashhad *** Iran Department of Internal Medicine Imam Reza Hospital Mashhad University of Medical Sciences Mashhad *** Iran Department of Pathology Omid Hospital Mashhad University of Medical Sciences Mashhad *** Iran Department of Surgery Omid Hospital Mashhad University of Medical Sciences Mashhad *** Iran Department of Oncology Omid Hospital and Cancer Research Center Mashhad *** Iran Gastroenterology Research Center Mashhad University of Medical Sciences Mashhad *** Iran

AIM： TO determine p15 promoter hypermethylation in gastric tumoral tissue and serum samples, its impact on p16-protein expression, and correlation with clinical and histological features. METHODS： Samples were obtained from 52 histologically confirmed cases of gastric adenocarcinoma. Gastric tissue and serum of 50 age- and sex-matched individuals with normal gastroscopy and biopsy were obtained as control samples. Methylation-specific polymerase chain reaction （MSP） was used to evaluate methylation status of p16 promoter, p16-protein expression was analyzed by immunohistochemical staining on paraffin-embedded sections. RESULTS： Methylation was detected in 44.2% （23/52） of tumoral tissues. 60.9% of them were also methylated in serum, i.e., 26.9% of all patients （14/52）. Methylation was not detected in tissue and sera of control samples. p16-protein expression was decreased in 61.5% of cases （32/52）, and was significantly associated with promoter hypermethylation （P 〈 0.001）. Methylation was significantly more frequent in higher pathological grades （P 〈 0.05）. Methylation was not associated with other clinicopathological features and environmental factors including Hpylori infection and smoking. CONCLUSION： p16 promoter hypermethylation is an important event in gastric carcinogenesis. It is the principle mechanism of p16 gene silencing. It is related to malignant tumor behavior. Detection of DNA methylation in serum may be a biomarker for early detection of gastric cancer.

关键词： Gastric cancer p16 Hypermethylation Methylation specific PCR