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A Test on Different Types of the Time Curve of Hardness Ratio of Gamma-Ray Bursts based on the Curvature Effect

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chinese Journal of Astronomy and Astrophysics 2008年第4期8卷 451-464页

作者： Lan-Wei Jia National Astronomical Observatories/Yunnan Observatory,chinese academy of sciences,Kunming 650011,china Graduate School of chinese academy of sciences,beijing 100049,china National Astronomical Observatories/ Yunnan Observatory Chinese Academy of Sciences Kunming 650011 China and Graduate School of chinese academy of sciences Beijing 100049 China

We analyzed a sample of 66 gamma-ray bursts （GRBs） and statistically confirmed the prediction on the time curve of the hardness ratio of GRBs made by Qin et al. based on the curvature effect. In their analysis, GRB pulses are divided into three types according to the shape of their raw hardness ratio （RHR） time curves, defined as to include the background counts to the signal counts, so as to make use of counts within small time intervals. Of the three types, very hard sources exhibit a perfect pulse-like profile （type 1）, hard bursts possess a pulse-like profile with a dip in the decay phase （type 2）, and soft bursts show no pulse-like profile but have only a dipped profile （type 3）. In terms of the conventional hardness ratio, type 3 sources are indeed generally softer than those of type 1 and type 2, in agreement with the prediction. We found that the minimum value of RHR is sensitive in distinguishing the different types. We propose that GRB pulses can be classified according to the minimum value of RHR and that the different type sources may be connected with different strengths of the shock or/and the magnetic field.

关键词： gamma-rays burst -- gamma-rays observations - methods statistical

Vilnius Photometry and Reddening of the Young Open Cluster NGC 6913

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chinese Journal of Astronomy and Astrophysics 2001年第4期1卷 333-343页

作者： Jun-Jie Wang and Jing-Yao Hu (National Astronomical Observatories, chinese academy of sciences, beijing 100012 beijing Astronomical Observatory, chinese academy of sciences, beijing 100012 chinese academy of sciences-Peking University Joint beijing As chinese academy of sciences-Peking University Joint beijing Astrophysical center Beijing 100871

stars in the NGC 6913 field with both UBV and Vilnius photometry are selected to be the sample. The membership probability of the stars is greater than 50%. The correlation among Vilnius photometry, UBV photometry and reddening in the cluster is reviewed. It is found that the photometry in the Vilnius X, Y and Z bands can be used to make rough spectral classification. The values of E(B - V) are well correlated with the Vilnius colors of X - Y, Y - Z, Z - V and V - S in NGC 6913. The ratio of (V - S)/(Y - Z) of the MPCM (Most Possible Cluster Members) is a constant (1.30 -±0.06), and has no effect on the values of E(B - V), (B - V)0 and V0. Comparing with the observational data of all the stars of NGC 6913 region, we propose that the value of (V - S)/(Y - Z) can probably be used to select the preliminary candidates of one open cluster. In addition, 12 variable stars are discovered in the NGC 6913 region, in which star #155 has a variation with an amplitude of 4.25 mag.

关键词： Galaxy: open clusters and associations - ISM: dust extinction

Value of ecosystem services in china

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chinese Science Bulletin 2000年第10期45卷 870-876页

作者： CHEN Zhongxin & ZHANG XinshiLaboratory of Quantitative Vegetation Ecology, Institute of Botany, chinese academy of sciences, beijing 100093, china Current address: Institute of Natural Resources and Regional Planning, chinese academy of agricultural sciences, beijing 100081, china Laboratory of Quantitative Vegetation Ecology Institute of Botany Chinese Academy of Sciences Beijing China

The function and services are the important components of the life-support system in theplanet, as well as the basic elements for sustainable development of environment and society. It is a must to evaluate it for incorporating it with the social-economic system. It is also an important approach to draw the public attention on the environmental and ecosystem conservation. In this study, the ecosystem function and services in china were estimated by employing the classification and economic parameters from Costanza et al. The type and area of terrestrial ecosystems were extracted from Vegetation Map of china (1:4 000 000), and then the distribution map of ecosystem services of china was drawn. According to our calculation, the total value of ecosystem services in china is 77 834.48×108 RMB yuan per annum. The value for terrestrial ecosystem is 56 098.46×108 yuan per annum, and that for marine ecosystem is 21 736.02×108 yuan per annum. The value of ecosystem services in china is 1.73 times bigger

关键词： ecosystem function service.

How is neuronal homeostasis maintained?

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生物物理学报 2009年第S1期25卷 45-46页

作者： Jin-Hui Wang Institute of Biophysics, chinese academy of sciences, beijing china 100101

Homeostasis in internal environment and cellular metabolism ensures cells’ functions to be stable in living organisms. Neuronal spike encoding in the brain needs to be precise

关键词： How is neuronal homeostasis maintained

Synthesis and Cation-Mediated Electron Transfer in Fluorescence Quenching of Donor-Acceptor Podands

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chinese Chemical Letters 2000年第9期11卷 767-770页

作者： Hua JIANG Hui Jun XU Institute of Photographic Chemistry, chinese academy of sciences, beijing, 100101 chinese Acad Sci Inst Photog Chem Beijing 100101 Peoples R China

Reduced rate constants of photoinduced electron transfer in intramolecular fluorescence quenching of donor-acceptor podands induced by cation-complexation are observed in the highly exothermic reactions.

关键词： electron transfer donor acceptor podands

Oxygen isotopic (^(17)O-^(18)O) heterogeneity in Archaean continental nucleus, North china Craton

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chinese Science Bulletin 1999年第24期44卷 2267-2269页

作者： LIU Jianzhong, ZHANG Fuqin, LI Chunlai and WANG Shijie Institute of Geochemistry , chinese academy of sciences , Guiyang 550002 , china Institute of Geophysics , chinese academy of sciences , beijing 100101 , china Institute of Geochemistry Chinese Academy of Sciences Guiyang China Institute of Geophysics Chinese Academy of Sciences Beijing China

The oxygen isotopic data for amphibolites from Archaean continental nucleus, North china Craton indicate that ( i ) the evolving lines structured by the data are parallel to the geoselenic evolving line, which means that the parent materials of these continental nucleus o-riginated from solar matter; ( ii ) different intercepts for these evolving lines manifest that oxy-

关键词： North china Craton oxygen isotope (I7O-18O ) heterogeneity.

Systematic distortion in cosmic microwave background maps

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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 100049 China center for Astrophysics Tsinghua University Beijing 100084 China Graduate University of chinese academy of sciences Beijing 100049 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

Prediction model for spring dust weather frequency in North china

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Science china Earth sciences 2008年第5期51卷 709-720页

作者： LANG XianMei center for Disastrous Climate Research and Prediction, Institute of Atmospheric Physics, chinese academy of sciences, beijing 100029, china center for Disastrous Climate Research and Prediction Institute of Atmospheric Physics Chinese Academy of Sciences Beijing 100029 China

It is of great social and scientific importance and also very difficult to make reliable prediction for dust weather frequency (DWF) in North china. In this paper, the correlation between spring DWF in beijing and Tianjin observation stations, taken as examples in North china, and seasonally averaged surface air temperature, precipitation, Arctic Oscillation, Antarctic Oscillation, South Oscillation, near surface meridional wind and Eurasian westerly index is respectively calculated so as to construct a prediction model for spring DWF in North china by using these climatic factors. Two prediction models, i.e. model-I and model-II, are then set up respectively based on observed climate data and the 32-year (1970 -2001) extra-seasonal hindcast experiment data as reproduced by the nine-level Atmospheric General Circulation Model developed at the Institute of Atmospheric Physics (IAP9L-AGCM). It is indicated that the correlation coefficient between the observed and predicted DWF reaches 0.933 in the model-I, suggesting a high prediction skill one season ahead. The corresponding value is high up to 0.948 for the subsequent model-II, which involves synchronous spring climate data reproduced by the IAP9L-AGCM relative to the model-I. The model-II can not only make more precise prediction but also can bring forward the lead time of real-time prediction from the model-I’s one season to half year. At last, the real-time predictability of the two models is evaluated. It follows that both the models display high prediction skill for both the interannual variation and linear trend of spring DWF in North china, and each is also featured by different advantages. As for the model-II, the prediction skill is much higher than that of original approach by use of the IAP9L-AGCM alone. Therefore, the prediction idea put forward here should be popularized in other regions in china where dust weather occurs frequently.

关键词： spring dust weather frequency prediction model iap9l-agcm hindcast experiment real-time prediction

Ionization state of cosmic hydrogen by early stars and quasars

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Research in Astronomy and Astrophysics 2009年第6期9卷 665-681页

作者： Xiao-Chun Mao1,2 1 National Astronomical Observatories, chinese academy of sciences, beijing 100012, china 2 Graduate University of chinese academy of sciences, beijing 100049, china National Astronomical Observatories Chinese Academy of Sciences Beijing 100012 China Graduate University of chinese academy of sciences Beijing 100049 China

Cosmic hydrogen is reionized and maintained in its highly ionized state by the ultraviolet emission attributed to an early generation of stars and quasars. The Lyα opacity observed in absorption spectra of high-redshift quasars permits more stringent constraints on the ionization state of cosmic hydrogen. Based on density perturbation and structure formation theory, we develop an analytic model to trace the evolution of the ionization state in the post-overlap epoch of reionization, in which the bias factor is taken into account. For quasars, we represent an improved luminosity function by utilizing a hybrid approach for the halo formation rate that is in reasonable agreement with the published measurements at 2 ≤ z ≤ 6. Comparison with the classic Press-Schechter mass function of dark matter halos, we demonstrate that the biased mass distribution indeed enhances star formation efficiency in the overdense environment by more than 25 per cent following the overlap of ionized bubbles. In addition, an alternative way is introduced to derive robust estimates of the mean free path for ionizing photons. In our model, star-forming galaxies are likely to dominate the ionizing background radiation beyond z = 3, and quasars contribute equally above a redshift of z ～ 2.5. From 5 ≤ z ≤ 6, the lack of evolution in photoionization rate can thus be explained by the relatively flat evolution in star formation efficiency, although the mean free path of ionizing photons increases rapidly. Moreover, in the redshift interval z ～ 2 - 6, the expected mean free path and Gunn-Peterson optical depth obviously evolve by a factor of ～ 500 and ～50 respectively. We find that the relative values of critical overdensities for hydrogen ionization and collapse could be 430% at z ≈2 and 2% at z ≈6, suggesting a rapid overlap process in the overdense regions around instant quasars following reionization. We further illustrate that the absolute estimates of the fraction of neutral hydrogen computed fr

关键词： cosmology theory -- formation galaxies -- quasars general -- diffuse radiation -- intergalactic medium