检索结果-南通市图书馆

Inconsistency between WMAP data and released map

在线全文

学校读者我要写书评

暂无评论

chinese Science Bulletin 2010年第10期55卷 907-909页

作者： liu hao1 & li tipei1,2,3 1 key laboratory of particle astrophysics,institute of high energy physics,chinese academy of sciences,beijing 100049,china 2 Department of physics & Center for astrophysics,Tsinghua University,beijing 100084,china 3 Department of Engineering physics & Center for astrophysics,Tsinghua University,beijing 100084,china key laboratory of particle astrophysics Institute of High Energy Physics Chinese Academy of Sciences Beijing China Department of physics & Center for astrophysics Tsinghua University Beijing China Department of Engineering physics & Center for astrophysics Tsinghua University Beijing China

A remarkable inconsistency between the calibrated differential time-ordered data (TOD) of the Wilkinson Microwave Anisotropy Probe (WMAP) mission,which is the input for map-making,and the cosmic microwave background (CMB) temperature maps published by the WMAP team is revealed,indicating that there must exist a serious problem in the map making routine of the WMAP *** inconsistency is easy to be confirmed without the use of WMAP map-making *** view of the importance of this issue for cosmology study,we invite readers to check it by themselves.

关键词：威尔金森微波各向异性探测器 WMAP 地图制作宇宙微波背景有序数据制作软件 TOD CMB

Systematic distortion in cosmic microwave background maps

在线全文

学校读者我要写书评

暂无评论

Science china(physics,Mechanics & Astronomy) 2009年第5期52卷 804-808页

作者： liu hao 1,3 &li tipei 1,2 1key laboratory of particle astrophysics,institute of high energy physics,chinese academy of sciences,beijing 100049,china 2Center for astrophysics,Tsinghua University,beijing 100084,china 3 Graduate University of chinese academy of sciences,beijing 100049,china key laboratory of particle astrophysics Institute of High Energy Physics Chinese Academy of Sciences Beijing China Graduate University of chinese academy of sciences Beijing China Center for astrophysics Tsinghua University Beijing China

To minimize instrumentally the induced systematic errors,cosmic microwave background(CMB)anisotropy experiments measure temperature differences across the sky using pairs of horn antennas, temperature map is recovered from temperature difference obtained in sky survey through a map-making *** inspect and calibrate residual systematic errors in the recovered temperature maps is important as most previous studies of cosmology are based on these *** analyzing pixel-ring coupling and latitude dependence of CMB temperatures,we find notable systematic devia- tion from CMB Gaussianity in released Wilkinson Microwave Anisotropy Probe(WMAP)*** detected deviation cannot be explained by the best-fit LCDM cosmological model at a confidence level above 99%and cannot be ignored for a precision cosmology study.

关键词： cosmology cosmic microwave background methods data analysis

Bifurcation timescales in power spectra of black hole binaries and ultraluminous X-ray sources

在线全文

学校读者我要写书评

暂无评论

Science china(physics,Mechanics & Astronomy) 2010年第S1期53卷 177-182页

作者： WANG TaiShan1 & li tipei1,2 1 Department of physics & Center for astrophysics,Tsinghua University,beijing 100084,china 2 key laboratory of particle astrophysics,institute of high energy physics,chinese academy of sciences,beijing 100049,china Department of physics & Center for astrophysics Tsinghua University Beijing China key laboratory of particle astrophysics Institute of High Energy Physics Chinese Academy of Sciences Beijing China

For black hole binaries(BHBs) and active galactic nuclei(AGNs),bifurcation timescales(BTs) Δtb exist,below which time-domain power is significantly higher than the corresponding Fourier ***-periodic oscillations(QPOs) are removed from the Fourier spectra of BHBs.A relationship between BT,black hole mass and bolometric luminosity is *** anti-correlation between BT and luminosity of Cyg X-1 is *** removing the QPOs,BTs are also obtained for two ultraluminous X-ray sources(ULXs),M82 X-1 and NGC5408 *** results support that they harbor intermediate mass black holes(IMBHs).

关键词： black hole binary ultraluminous X-ray source power spectral density data analysis

Hard X-ray lags of Cygnus X-1 on short timescales

在线全文

学校读者我要写书评

暂无评论

Science china(physics,Mechanics & Astronomy) 2010年第S1期53卷 150-152页

作者： JIN Jing1,LU Yu2,3,QU JinLu2 & li tipei1,2 1 Department of Engineering physics & Center for astrophysics,Tsinghua University,beijing 100084,china 2 key laboratory of particle astrophysics,institute of high energy physics,chinese academy of sciences,beijing 100049,china 3 Graduate University of chinese academy of sciences,beijing 100049,china Department of Engineering physics & Center for astrophysics Tsinghua University Beijing China key laboratory of particle astrophysics Institute of High Energy Physics Chinese Academy of Sciences Beijing China Graduate University of chinese academy of sciences Beijing China

Calculating the time lags over different timescales using the cross-correlation technique may lead to a biased estimate of small *** a timescale for lightcurve binning,we propose to subtract the local average instead of the global average during the cross-correlation,in order to filter variations on timescales larger than the bin *** new method allows us to make an unbiased estimate of the time lags using RXTE/PCA data on timescales as small as-5 ms,where the Fourier technique becomes *** calculate the time lag spectra of Cygnus X-1 at different spectral states with the new method,and find that the source appears to have similar X-ray lags on small timescales independent of its spectral states.

关键词： spectral lags Cygnus X-1 data analysis

Compression behavior of Zr_(41)Ti_(14)Cu_(12.5)Ni_(10)Be_(22.5) bulk metallic glass up to 24 GPa

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3期48卷 319-324页

作者： li Gong 1, 2 , ZHAN Zaiji 2 , liu Jing 3 , YUN Jinku 1 , SUN liling 2 , liu Riping 1 , ZHANG Jun 2 & WANG Wenkui 1, 2 1. key laboratory of Metastable Materials Science and Technology, Yanshan University, Qinhuangdao 066004, china 2. Center for Condensed Matter physics, institute of physics, chinese academy of sciences, beijing 100080, china 3. BSRF, institute of high energy physics, chinese academy of sciences, beijing 100039, china key laboratory of Metastable Materials Science and Technology Yanshan University Qinhuangdao China Center for Condensed Matter physics Institute of Physics Chinese Academy of Sciences Beijing China BSRF Institute of High Energy Physics Chinese Academy of Sciences Beijing China

The compression of a Zr41Ti14Cu12.5Ni10Be22.5 bulk metallic glass (BMG) is investigated at room temperature up to 24 GPa using in-situ high pressure energy dispersive X-ray diffraction with a synchrotron radiation source. The pressure-induced structural relaxation is exhibited. It is found that below about 8 GPa, the existence of excess free volume contributes to the rapid structural relaxation, which gives rise to the rapid volumetric change, and the structural relaxation results in the structural stiffness under higher pressure.

关键词： bulk metallic glass, high pressure, structural relaxation, synchrotron radiation.

Simulation of the in-flight calibration of the collimator alignment and PSF for HXMT

在线全文

学校读者我要写书评

暂无评论

Science china(physics,Mechanics & Astronomy) 2010年第S1期53卷 47-50页

作者： XIONG Shaolin,li XinQiao,QU JinLu & LU FangJun key laboratory for particle astrophysics,institute of high energy physics,chinese academy of sciences(CAS),beijing 100049,china key laboratory for particle astrophysics Institute of High Energy Physics Chinese Academy of Sciences (CAS) Beijing China

The Hard X-ray Modulation Telescope(HXMT) is an X-ray astronomical satellite in 1-250 keV,consisting of three collimated *** present the in-flight calibration approach of the collimator alignment and Point Spread Function(PSF) for HXMT,using both the direct fitting method and the imaging *** to observational simulations of the Crab Nebula,we find that these two methods produce almost the same calibration accuracy of the alignment,and with a one-day scanning observation,the alignment can be calibrated to better than 0.45' and 0.1' along the wide and narrow directions of the Field of View(FOV) for a detector module,which corresponds to a localization accuracy of better than 0.1' and meets the scientific requirement.

关键词： HXMT alignment PSF calibration

The time lag spectrum of Cir X-1 on its normal branch

在线全文

学校读者我要写书评

暂无评论

Science china(physics,Mechanics & Astronomy) 2010年第S1期53卷 60-63页

作者： QU JinLu1,LU Yu1,2,DING GuoQiang3,ZHANG Fan1,LEI YaJuan1 & li ZhiBing1 1 key laboratory for particle astrophysics,institute of high energy physics,chinese academy of sciences,beijing 100049,china 2 Graduate University of chinese academy of sciences,beijing 100049,china 3 Urumqi Observatory,NAOC Urumqi 830011,china key laboratory for particle astrophysics Institute of High Energy Physics Chinese Academy of Sciences Beijing China Graduate University of chinese academy of sciences Beijing China Urumqi Observatory NAOC Urumqi China

In the radiation-hydrodynamics model,the time lag and fractional root-mean-squared(rms) amplitude as a function of emitted photon energy should show a minimum on the normal branch *** has been seen in the Z-sources Cyg X-2 and GX ***,using the observations from the Rossi X-ray Timing Explorer(RXTE),we study the energy dependence of normal branch QPOs in the peculiar Z-source Cir *** discuss the results in the context of radiation-hydrodynamics and the Comptonization model.

关键词： Cir X-1 temporal variability QPO time lag

The flux modulation of INTEGRAL

在线全文

学校读者我要写书评

暂无评论

Science china(physics,Mechanics & Astronomy) 2010年第S1期53卷 110-113页

作者： CHEN YuPeng,ZHANG Shu,WANG JianMin,li tipei & QU JinLu laboratory for particle astrophysics,institute of high energy physics,beijing 100049,china laboratory for particle astrophysics Institute of High Energy Physics Beijing China

We have analyzed International Gamma-Ray astrophysics laboratory(INTEGRAL) data corresponding to observations of the high mass X-ray binary(HMXB) V0332+53 during its huge outburst which occurred in 2004-2005,and found that there is a quasi periodic signal with ultra low frequency of roughly 4-5×10-5 Hz in the *** feature is revealed through a series of consistent analyses of imagings and fittings of the energy spectrum for each science window(SCW),and shows up in the corresponding light *** analysis of the power spectrum also provides a hint of a power peak located around 4×10-5 Hz,after subtracting off the linear trend of the light curve,and shows the consistency with the previous analyses.A similar feature shows up in our analysis of the light curve of Crab in hexagonal dithering ***,an instrumental effect on the flux modulation might exist in the INTEGRAL data product of different levels:imaging,spectral fitting and light curve analysis,at least for the observational mode of hexagonal *** an effect is,to our knowledge,not yet available in the current literature.

关键词： X-ray source individual V0332+53

Correlation of Behavior Changes and BOLD Signal in Alzheimer-like Rat Model

在线全文

学校读者我要写书评

暂无评论

Acta Biochimica et Biophysica Sinica 2004年第12期36卷 803-810页

作者： Zheng-Hui HU#, Xiao-Chuan WANG1#, li-Yun li3, Mai-li liu3, Rong liu1, Zhiqun liNG1, Qing TIAN1, Xiao-Wei TANG, Yi-Gen WU2*, and Jian-Zhi WANG1* Department of physics and Bio-X disciplinary laboratory, Zhejiang University, Hangzhou 310027,china 1 Department of Pathophysiology, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430030, china 2institute of high energy physics and key laboratory of Nuclear Analysis Techniques, chinese academy of sciences, P.O. Box 918, beijing 100039, china 3Wuhan institute of physics and Mathematics, State key laboratory of Magnetic Resonance and Atomic and Molecular physics, chinese academy of sciences, Wuhan 430071, china Department of physics and Bio-X disciplinary laboratory Zhejiang UniversityHangzhou 310027China Department of Pathophysiology Tongji Medical College Huazhong University of Science and TechnologyWuhan 430030 China Wuhan institute of physics and Mathematics State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics Chinese Academy of SciencesWuhan 430071 China institute of high energy physics and key laboratory of Nuclear Analysis Techniques Chinese Academy of SciencesP.O. Box 918 Beijing 100039 China

To explore a potential means for the early diagnosis of Alzheimer disease, we studied the relationship of resting T2* signal and tau hyperphosphorylation/spatial memory deficit. The rat model with tau hyperphosphorylation and spatial memory deficit was established by bilateral hippocampi injection of isoproterenol (IP). Then, the correlative alteration between resting T2* signal and spatial memory retention was assessed with blood oxygenation level dependent (BOLD) functional magnetic resonance imaging (fMRI) study and Morris Water Maze test, and Western blot was employed to confirm tau hyperphosphorylation. The analysis showed following results. (1) Tau phosphorylation at Ser396/Ser404 and Ser199/Ser202 was signifi- cantly increased in IP-injected rats as detected by PHF-1 and tau-1, respectively. (2) An AD-like spatial memory retention disturbance was induced at 24 h after isoproterenol injection. (3) A sensitivity threshold of resting T2* signal intensity, which separated the IP-treated rats from vehicle control, was obtained by applying linear regression analysis, and an estimated sensitivity statistical threshold was at 32.62. These results suggest that resting T2* signal may serve as a noninvasive quantitative marker in predicting AD-like spatial memory deficits and tau hyperphosphorylation.

关键词： Alzheimer disease (AD) functional magnetic resonance imaging (fMRI) isoproterenol (IP) Morris Water Maze diagnosis