检索结果-南通市图书馆

fMRI time series analysis based on stationary wavelet and spectrum analysis

在线全文

学校读者我要写书评

暂无评论

Progress in Natural Science:Materials International 2006年第11期16卷 1171-1176页

作者： ZHI Lianhe~ 1,2,3., ZHAO Xia~4, SHAN Baoci~1**, PENG Silong~5, YAN Qiang~1, YUAN Xiuli~1 and TANG Xiaowei~ 1,6 (1. Key Laboratory of Nuclear Analysis Techniques, Institute of High Energy physics, Chinese Academy of Sciences, Beijing 100049, china 2. Graduate School of Chinese Academy of Sciences, Beijing 100049, china 3. Department of physics, zhoukou normal university, zhoukou 4.6100, china 4. Research Imaging Center, university of Texas Health Science Center, San Antonio, Texas 78229, USA 5. National ASIC Design and Engineering Center, Institute of Automation, Chinese Academy of Sciences, Beijing 100049, china 6. Department of physics, Zhejiang university, Hangzhou 3.0027, china) [a]Key Laboratory of Nuclear Analysis Techniques Institute of High Energy Physics Chinese Academy of Sciences Beijing China [b]Graduate School of Chinese Academy of Sciences Beijing China [c]Department of physics Zhoukou Normal University Zhoukou China [d]Research Imaging Center University of Texas Health Science Center San Antonio Texas USA [e]National ASIC Design and Engineering Center Institute of Automation Chinese Academy of Sciences Beijing China [f]Department of physics Zhejiang University Hangzhou China

The low signal to noise ratio (SNR) of functional MRI (fMRI) prefers more sensitive data analysis methods. Based on stationary wavelet transform and spectrum analysis, a new method with high detective sensitivity was developed for analyzing fMRI time series, which does not require any prior assumption of the characteristics of noises. In the proposed method, every component of fMRI time series in the different time-frequency scales of stationary wavelet transform was discerned by the spectrum analysis, then the components from noises were removed using the stationary wavelet transform, finally the components of real brain activation were detected by cross-correlation analysis. The results obtained from both simulated and in vivo visual experiments illustrated that the proposed method has much higher sensitivity than the traditional cross-correlation method.

关键词： fMRI stationary wavelet transform spectrum analysis data analysis.

Optimal reactions for the synthesis of superheavy nucleus ^(270)Hs

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Science china(physics,Mechanics & Astronomy) 2006年第6期49卷 641-648页

作者： LIU Zuhua1,3.& BAO Jingdong1,2 1. Key Laboratory of Beam Technology and Material Modification of Ministry of Education, Beijing normal university, Beijing 100875, china 2. {3. Department, Beijing normal university, Beijing 100875, china 3. china Institute of Atomic Energy, Beijing 102413. china Key Laboratory of Beam Technology Material Modification of Ministry of Education Beijing Normal University Beijing 100875 China physics Department Beijing Normal University Beijing 100875 China china Institute of Atomic Energy Beijing 102413 China

The superheavy nucleus 270Hs is expected to be a “double-magic” deformed nucleus. We have calculated its cross sections of evaporation residue for the reactions 248Cm(26Mg,4n)270Hs, 244Pu(3.Si,4n)270Hs, 23.U(3.S,4n)270Hs and 226Ra(48Ca,4n)270Hs using a two-parameter Smoluchowski equation. It is found from our results that 226Ra(48Ca,4n)270Hs and 23.U(3.S,4n)270Hs are two optimal reactions for the synthesis of the superheavy nucleus 270Hs due to their large negative Q-values.

关键词： diffused fusion barrier,Smoluchowski equation,superheavy nuclei.

Accurate studies on the full vibrational energy spectra and molecular dissociation energies for some electronic states of N_(2)molecule

在线全文

学校读者我要写书评

暂无评论

Science china(physics,Mechanics & Astronomy) 2005年第4期48卷 385-398页

作者： REN Weiyi1,2, SUN Weiguo1, HOU Shilin3.& FENG Hao4 1. Institute of physics, College of Chemical Engineering, Sichuan university, Chengdu 610065, china 2. Institute of Theoretical physics, Xihua normal university, Nanchong 63.002, china 3. Department of physics, china Oceanography university, Qingdao 266003. china 4. College of physics, Sichuan university, Chengdu 610065, china 1. Institute of physics College of Chemical Engineering Sichuan University 610065 Chengdu China 2. Institute of Theoretical physics Xihua Normal University 637002 Nanchong China 3. Department of physics China Oceanography University 266003 Qingdao China 4. College of physics Sichuan University 610065 Chengdu China

It is usually very difficult to directly obtain molecular dissociation energy De and all accurate high-lying vibrational energies for most diatomic electronic states using modern experimental techniques or quantum theories, and it is also very difficult to give accurate analytical expression for diatomic molecular dissociation energy. This study proposes a new analytical formula for obtaining accurate molecular dissociation energy based on the LeRoy and Bernstein’s energy expression in dissociation limit. A set of full vibrational energy spectra for some electronic states of N2 molecule are studied using the algebraic method (AM) suggested recently, and the corresponding accurate molecular dissociation energies are evaluated using the proposed new formula and high-lying AM vibrational energies. The results show that the AM spectra and the new theoretical dissociation energies agree excellently with experimental data, and thereby providing a new physical approach to generating accurate dissociation energies for electronic states of diatomic molecules.

关键词： vibrational energy, dissociation energy, nitrogen molecule, algebraic method.

X-ray spectra induced in highly charged 40Ar^q+ interacting with Au surface

在线全文

学校读者我要写书评

暂无评论

Science china(physics,Mechanics & Astronomy) 2006年第2期49卷 203-212页

作者： ZHANG Xiao’an1,2, XIAO Guoqing1, YANG Zhihu1, CHEN Ximeng3. ZHAO Yongtao1, LI Fuli4, ZHANG Yinping1, CUI Ying3. ZHANG Hongqiang3. XU Xu3. SHAO Jianxiong3.& ZHAN Wenlong11. Institute of Modern physics, Chinese Academy of Sciences, Lanzhou 73.000, china 2. Department of physics, Xianyang {3. university, Xianyang 712000, china 3. Department of Modern physics, Lanzhou university, Lanzhou 73.000, china 4. Department of Applied physics, Xi’an Jiaotong university, Xi’an 710049, china 1. Institute of Modern physics Chinese Academy of Sciences Lanzhou 730000 China 2. Department of physics Xianyang Normal University Xianyang 712000 China 3. Department of Modern physics Lanzhou University Lanzhou 730000 China 4. Department of Applied physics Xi’an Jiaotong University Xi’an 710049 China

By use of optical spectrum technology, the spectra of X-ray induced by highly charged 40Arq+ ions interacting with Au surface have been studied. The results show that the argon Kα X-ray were emitted from the hollow atoms formed below the surface. There is a process of multi-electron exciting in neutralization of the Ar16+ion, with electronic con-figuration 1s2 in its ground state below the solid surface. The yield of the projectile Kα X-ray is related to its initial electronic configuration, and the yield of the target X-ray is related to the projectile kinetic energy.

关键词： highly charged ion hollow multi-electron excitation X- ray.

Proton induced X-ray emission (PIXE) analysis of sources of porcelain body of Ru Guan and Jun Guan porcelains

在线全文

学校读者我要写书评

暂无评论

Science china(physics,Mechanics & Astronomy) 2006年第4期49卷 411-420页

作者： LI Guoxia1, ZHAO Weijuan1, LI Rongwu2, SUN Hongwei1, GUO Min1, WANG Yanfang1, LIU Hui1, ZHAO Qingyun3. SUN Xinmin3. ZHAO Wenjun3.& CHENG Huansheng4 1. Faculty of Physical Engineering, Zhengzhou university, Zhengzhou 450052, china 2. Department of physics, Beijing {3. university, Beijing 100875, china 3. Institute of Cultural Relic and Archaeology of Henan Province, Zhengzhou 450000, china 4. Institute of Modern physics, Fudan university, Shanghai 20043., china Faculty of Physical Engineering Zhengzhou University Zhengzhou 450052 China Department of physics Beijing Normal University Beijing 100875 China Institute of Cultural Relic Archaeology of Henan Province Zhengzhou 450000 China Institute of Modern physics Fudan University Shanghai 200433 China

3. samples of Ru Guan porcelain body and 50 samples of Jun Guan porcelain body (both kinds being in different body colors) were selected with the purpose of finding out the source of raw materials and their classification relationship so as to search for ways of non-destructive discrimination. Proton induced X-ray emission (PIXE) has been applied to these samples to determine their chemical elements. The data of seven major chemical elements collected from these samples were further studied through fuzzy cluster analysis. Results indicate that the origin of raw materials of Jun Guan porcelain body samples is comparatively more concentrated in certain places, while that of Ru Guan porcelain body samples is scattered about. The places of origin of raw materials of the majority of Ru Guan and Jun Guan porcelain body samples have something in common, but some differences still exist. It might be an important way for non-destructive discrimination among Ru Guan and Jun Guan porcelains by combining PIXE with fuzzy cluster analysis.

关键词： Ru Guan and Jun Guan porcelain, source of porcelain body, PIXE, fuzzy cluster analysis, non-destructive discrimination.

Role of gallium wetting layer in high-quality ZnO growth on sapphire (0001) substrates

在线全文

学校读者我要写书评

暂无评论

Science china(physics,Mechanics & Astronomy) 2004年第5期47卷 612-620页

作者： ZENG Zhaoquan1,3. WANG Yong2, DU Xiaolong1, MEI Zengxia1, KONG Xianghe3. JIA Jinfeng1, XUE Qikun1 & ZHANG Ze2, 4 1. State Key Laboratory for Surface physics, Institute of physics, Chinese Academy of Sciences, Beijing 100080, china 2. Laboratory of Electron Microscopy, Institute of physics, Chinese Academy of Sciences, Beijing 100080, china 3. College of physics and Engineering, Qufu normal university, Qufu 273.65, china 4. Beijing university of Technology, Beijing 100022, china 1. State Key Laboratory for Surface physics Institute of Physics Chinese Academy of Sciences 100080 Beijing China 2. College of physics and Engineering Qufu Normal University 273165 Qufu China 3. Laboratory of Electron Microscopy Institute of Physics Chinese Academy of Sciences 100080 Beijing China 4. Beijing university of Technology 100022 Beijing China

A Ga wetting layer was used to modify the surface structure of sapphire (0001) substrate to prepare high-quality ZnO film by radio frequency plasma-assisted molecule beam epitaxy. We found that this Ga layer plays a crucial role in eliminating 3. rotation domains, controlling polarity and decreasing defect density in ZnO epilayers, as demonstrated by in situ reflection high energy electron diffraction, ex situ high resolution X-ray diffraction and high resolution cross-sectional transmission electron microscopy. Zn-polar film of ZnO was determined by convergent beam electron diffraction. A Ga bilayer model is proposed to understand the effects of the Ga wetting layer on high-quality ZnO growth.

关键词： Ga wetting layer, sapphire, polarity, defect density, zinc oxide, rf-MBE, RHEED, HRXRD, TEM, CBED.

The dynamical properties of Rydberg hydrogen atom near a metal surface

在线全文

学校读者我要写书评

暂无评论

Science china(physics,Mechanics & Astronomy) 2005年第6期48卷 667-675页

作者： GE Meihua1, ZHANG Yanhui1, WANG Dehua2, DU Mengli3.& LIN Shenglu1 1. College of physics and Electronics, Shandong normal university, Jinan 250014,{3. 2. Department of Mathematics and physics, Shandong Institute of Architecture and Engineering, Jinan 250014,{3. 3. Institute of Theoretical physics, Chinese Academy of Sciences, Beijing 100080,{3. 1. College of physics and Electronics Shandong Normal University 250014 Jinan China 2. Department of Mathematics and physics Shandong Institute of Architecture and Engineering 250014 Jinan China 3. Institute of Theoretical physics Chinese Academy of Sciences 100080 Beijing China

The dynamical properties of Rydberg hydrogen atom near a metal surface are presented by using the methods of phase space analysis and closed orbit theory. Transforming the coordinates of the Hamiltonian, we find that the phase space of the system is divided into vibrational and rotational region. Both the Poincaré surface of section and the closed orbit theory verify the same conclusion clearly. In this paper we choose the atomic principal quantum number as n = 20. The dynamical character of the exited hydrogen atom depends sensitively on the atom-surface distance d. When d is sufficiently large, the atom-surface potential can be expressed by the traditional van der Waals force and the system is integrable. When d becomes smaller, there exists a critical value dc. For d > dc, the system is near-integrable and the motion is regular. While chaotic motion appears for d < dc, and the system tends to be non-integrable. The trajectories become unstable and the electron might be captured onto the metal surface.

关键词： Rydberg hydrogen atom, van der Waals interaction, Poincaré surface of section, closed orbit theory, chaos.

Implementation of a multiple round quantum dense coding using nuclear magnetic resonance

在线全文

学校读者我要写书评

暂无评论

Science china(physics,Mechanics & Astronomy) 2005年第6期48卷 706-715页

作者： ZHANG Jingfu1, XIE Jingyi2, WANG Chuan1, DENG Zhiwei3. LU Zhiheng4, & LONG Guilu1,5 1. Key Laboratory For Quantum Information and Measurements of MOE, Department of physics, Tsinghua university, Beijing 100084,china 2. Department of Materials Science and Engineering, Beijing {3. university, Beijing 100875, china 3. Testing and Analytical Center, Beijing {3. university, Beijing 100875,china 4. Department of physics, Beijing {3. university, Beijing 100875, china 5. Key Laboratory For atomic and Molecular Nanosciences, Tsinghua university, Beijing 100084,china 1. Key Laboratory For Quantum Information and Measurements of MOE Department of Physics Tsinghua University 100084 Beijing China 2. Department of Materials science and Engineering Beijing Normal University 100875 Beijing China 3. Testing and Analytical Center Beijing Normal University 100875 Beijing China 4. Department of physics Beijing Normal University 100875 Beijing China 5. Key Laboratory For Atomic and Molecular Nanosciences Tsinghua University 100084 Beijing China

A multiple round quantum dense coding scheme based on the quantum phase estimation algorithm is proposed and implemented in a three qubit nuclear magnetic resonance (NMR) quantum computer. Using an m + 1 qubit system, Bob can transmit one of 2m+1 messages to Alice, through manipulating only one qubit and exchanging it between Alice and Bob for m rounds. The information capacity is enhanced to m + 1 bits as compared to m bits in a classical scheme. The scheme has been demonstrated in NMR system, and the experimental results show a good agreement between theory and experiment.

关键词： quantum dense coding, multiple round, nuclear magnetic resorance

Probability parametric imaging with DCE-MRI data to identify prostate cancer in the peripheral zone

在线全文

学校读者我要写书评

暂无评论

Progress in Natural Science:Materials International 2006年第9期16卷 948-953页

作者： HUANG Xinrui, WANG Qiang, XU Yufeng, WANG Xiaoying and BAO Shanglian ( The Key Laboratory of Medical physics and Engineering, Peking university, Beijing 100871, china The Medical School of Peking university, Beijing 100083. china 3. The First Hospital of Peking university, Beijing 10003., china) [a]The key Laboratory of Medical physics and Engineering Peking University Beijing China [b]The Medical School of Peking university Beijing China [c]The First Hospital of Peking university Beijing China

To quantitatively analyze prostate dynamic contrast-enhanced magnetic resonance images (DCE-MRI), a retrospective study was carried out to construct a mathematical model to predict whether a lesion is cancerous or not. With known diagnosis of 52 re-gions-of-interest (10 malignant, 26 benign and 16 normal) in peripheral zone (PZ) of prostate from 18 patients undergoing needle biopsy and 8 normal volunteers, we combined feature parameters (k1, k2 and tp) from the linear-slope model with logistic regression to determine the statistical probability model. Prostate cancerous probability maps were derived using the model on each subject to examine the correlation between the model-based prediction and the known diagnosis. Compared the model prediction results of 52 regions-of-interest with the histopathologic results, the total agreement rate was 90.4 % ; the agreement rate was 60 % for the malignant and 97. 6 % for the nonmalignant. The diagnostic results only referencing the probability maps by two radiologists showed a high agreement in tissue characteristics and lesion location with the combining results from other diagnostic techniques such as PSA (prostate specific antigen) level and MRS (magnetic resonance spectroscopy) .

关键词： time-intensity curve prostate DCE-MRI logistic regression probability parametric image.