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X-ray flares of γ-ray bursts: Quakes of solid quark stars?

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Science china(Physics,Mechanics & Astronomy) 2009年第2期52卷 315-320页

作者： XU RenXin1 & LIANG EnWei2 1 School of Physics and State Key Laboratory of Nuclear Physics and Technology, peking university, beijing 100871, china 2.department of Physics, Guangxi university, Nanning 530004, china 1. School of Physics and State Key Laboratory of Nuclear Physics and Technology Peking University Beijing 100871 China 2. department of Physics Guangxi University Nanning 530004 China

A star-quake model is proposed to understand X-ray flares of both long and short γ-ray bursts (GRBs) in a solid quark star regime. Two kinds of central engines for GRBs are available if pulsar-like stars are actually (solid) quark stars, i.e., the SNE-type GRBs and the SGR-type GRBs. It is found that a quark star could be solidified about 103 to 106 s later after its birth if the critical temperature of phase transi- tion is a few Metga-electron-volts, and then a new source of free energy (i.e., elastic and gravitational ones, rather than rotational or magnetic energy) could be possible to power GRB X-ray flares.

关键词： γ-rays bursts: X-rays neutron stars elementary particles

SUPERCONDUCTIVITY IN La1.85Sr0.15Cu1-xZnxO4

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低温物理学报 1993年第6期15卷 425-426页

作者： Fusui LiuPhysics department, peking university, beijing, 100871 北京大学北京

Based on the multiple exchange-mediated interaction mechanism of high- Tc superconductivity and the Abrikosov-Gorkov theory of magnetic impurity superconductors, this paper quantitatively explains the Zn-substitution ... 详细信息

关键词： Zn SUPERCONDUCTIVITY IN La x)ZnxO4 Cu Sr

Flux of dimethylsulfide in the Jiaozhou Bay,china

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Journal of Environmental Sciences 1997年第1期9卷 80-85页

作者： Hu Min Tang Xiaoyan Center of Environmental Sciences,peking university,beijing 100871,chinaLi Jinlong Yu Zhongju department of Technical Physics,peking university,beijing 100871,china Center of Environmental Sciences Peking University Beijing 100871 China department of Technical Physics Peking University Beijing 100871 China

Seasonal measurements of dimethylsulfide(DMS)in surface waters were carried out during 1993-1994 in the Jiaozhou Bay.A seasonal variation is observed for DMS concentrations in seawater,ranging from 0.6 to 8.97 nmol S/L with the highest values in spring.A factor of 4 was measured for DMS concentrations with mean concentrations of 5.85 nmol S/L or 6.58 nmol S/L in spring and 1.40nmol S/L in winter.A sea-to-air flux of DMS also showed a seasonal variation.

关键词： dimethyl sulfide flux seawater atmosphere.

Oblique Derivative Problems for NonlinearEquations of Mixed Type in General Domains

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Communications in Nonlinear Science and Numerical Simulation 1998年第3期3卷 148-151页

作者： Guochun WEN and Maoying TAIN(department of Mathematics, peking university, beijing 100871, china)e-mail: wengc@*** department of Mathematics Peking University Beijing 100871 China

The paper deals with oblique derivative boundary value problem for secondorder nonlinear equations of mixed (elliptic-hyperbolic ) type in general domains. By usingthe method of complex analysis, the uniqueness and ex... 详细信息

关键词： oblique derivative problems nonlinear equations of mixed type general domains

On the Markov equivalence of maximal ancestral graphs

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Science china Mathematics 2005年第4期48卷 548-562页

作者： ZHAO Hui, ZHENG Zhongguo & LIU Baijun School of Mathematical Sciences, peking university, beijing 100871, china department of Statistics, Central china Normal university, Wuhan 430079, china 1. School of Mathematical Sciences Peking University 100871 Beijing China

Necessary and sufficient conditions for a maximal ancestral graph (MAnG)to be Markov equivalent to another MAnG and to a DAG are provided respectively. Also a polynomial-time algorithm for converting a MAnG into its e... 详细信息

关键词： maximal ancestral graph, Markov equivalence, minimal collider path, m-separation.

On　Algebraic　Differential　Equations

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北京大学学报(自然科学版) 1996年第3期 8-24页

作者： CHUANG \ Chitai (department of Mathematics, peking university, beijing, 100871)

研究了一般形式的代数微分方程的全纯解的增长性，并证明了几个有关定理。证明是根据一个关于Ｗｉｍａｎ－Ｖａｌｉｒｏｎ理论的定理

关键词：代数微分方程 Wiman-Valiron理论

Dehydration melting of solid amphibolite at 2.0 GPa: Effects of time and temperature

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Science china Earth Sciences 2005年第8期48卷 1120-1133页

作者： ZHOU Wenge1, XIE Hongsen1, LIU Yonggang1, ZHENG Xiaogang1, ZHAO Zhidan2 & ZHOU Hui3 1. Laboratory of Material in the Earth’s Interior, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang 550002, china 2. department of Geology, china university of Geosciences, beijing 100083, china 3. department of Geology, peking university, beijing 100871, china 1. Laboratory of Material in the Earth’s Interior Institute of Geochemistry Chinese Academy of Sciences 550002 Guiyang China 2. department of Geology China University of Geosciences 100083 Beijing China 3. department of Geology Peking University 100871 Beijing China

Two sets of dehydration-melting with a natural solid amphibolite, collected from North Himalayan structure zone, Tibet, have been carried out in multi-anvil apparatus at 2.0 GPa and 800―1000℃, for 12―200 h. One is keeping the pressure at 2.0 GPa and the annealing time of 12 h, changing the temperature (800―1000℃). The other is keeping the pressure at 2.0 GPa and temperature at 850℃, varying the annealing time (12―200 h). The products are inspected with microscope and electron probe. The results indicate that at 2.0 GPa, annealing time of 12 h, garnets, melts and clinopyroxenes occur in amphibolite gradually with increasing temperature and the chemical compositions of melt vary from tonalite to granodiorite, and then to tonalite. However, at 2.0 GPa and 850℃, with the annealing time increasing, the garnets, melts and cli-nopyroxenes also occur in amphibolite gradually and the chemical compositions of melt vary from tonalite to granodiorite. In both cases, melts interconnect with each other when the contents of melt are over the 5 vol.%. the viscosities of the melt produced in amphibolite at temperature higher than 850℃ are on a level with 104 Pa·s. The interconnected melt with such a viscosity may segregate from the source rock and form the magma over reasonable geological time. Therefore, it is believed that at the lower part of the overthickened crust, the tonlitic and grano-dioritic magma may be generated through the dehydration melting of amphibolite.

关键词： solid amphibolite, high pressure, high temperature, time, partial melting.

L~∞ CONVERGENCE OF QUASI-CONFORMING FINITE ELEMENTS FOR THE BIHARMONIC EQUATION

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Journal of Computational Mathematics 1995年第2期13卷 108-122页

作者： Wang Ming (department of Mathematics, peking university, beijing, china) 北京大学数学系北京

In this paper we consider the L∞ convergence for quasi-conforming finite ele-ments solving the boundary value probzlems of the biharmonic equation and give the nearly optimal order L∞ estimates.

关键词： Biharmonic equations Vertices Rectangles Interpolation Technology Polynomials Estimation methods Weighting functions Greens function Mathematical inequalities

Population pharmacokinetic model of valproate and prediction of valproate serum concentrations in children with epilepsy

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Acta Pharmacologica Sinica 2004年第12期25卷 10-17页

作者： De-chun JIANG, Li WANG2.department of Pediatrics, peking university First Hospital, TherapeuticDrug Monitoring and Clinical Toxicology, Center of peking university, beijing 100034, china department of Pediatrics Peking University First Hospital Therapeutic Drug Monitoring and Clinical Toxicology Center of Peking University Beijing 100034 China

AIM: Using sparse data of valproate (VPA) serum concentrations to build a population pharmacokinetic (PPK) model of VPA in Chinese children with epilepsy and to predict serum concentrations for new patients using a Bayesian approach. METHODS: Two hundred epileptic children, whose VPA serum concentrations were collected, were divided randomly into two groups (A and B, n=100 each). The PPK parameter values of group A were calculated to establish a PPK Model by using the NPEM Program of USC*PACK software. Based on it, VPA serum concentrations of group B were predicted with the Bayesian Fitting Program of the USC*PACK software. To assess the accuracy and precision of prediction, a paired-comparisons t-test was run between predicted and ob- served concentrations, and then the mean prediction error (MPE), mean square prediction error (MSPE), root mean square prediction error (RMSPE), and coincidence rates for different percentages of prediction error were all calculated. RESULTS: Optimum PPK parameters were: Ka, 2.522±2.743 h-1; Vs, 0.329±0.496 L/kg; and Kel, 0.0438±0.0384 h-1. For group B, there was no significant difference between predicted and observed concentrations. MPE was -0.43 mg/L, MSPE was 115.40 (mg/L)2, and RMSPE was 5.47 mg/L. The coincidence rates for percent- ages of prediction error, which were less than 5 %, 10 %, 15 %, 20 %, 25 %, and 30 %, were 62 %, 74 %, 82 %, 85 %, 89 %, and 93 %, respectively. CONCLUSION: A PPK model of VPA in epileptic children was successfully established. Based on it, VPA serum concentrations can be predicted accurately with a Bayesian approach.

关键词： pharmacokinetics valproic acid epilepsy Bayes theorem USC*PACK software