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Can the inner gap sparking take place in millisecond pulsars?

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Chinese Journal of astronomy and Astrophysics 2003年第5期3卷 443-452页

作者： Hong-Guang Wang, Guo-Jun Qiao and ren-xin xudepartment of astronomy, peking university, beijing 100871 Department of astronomy Peking University Beijing 100871

The inner vacuum gap model has become the foundation stone of most theorieson pulsar radio emission. The fundamental picture of this model is the sparking, which wasconjectured to be induced by magnetic absorption of background gamma photons. However, a questionis, can the sparking be triggered in the millisecond pulsars (MSPs) with magnetic fields (B) onlyabout 10~8 G? We investigate this problem by including the pair production above the inner *** the assumption that the magnetic field is dipolar, our results show the background gamma-rayemission can not be the key factor that triggers the sparking, at least not in MSPs with B ～ 10~8G, if the temperature in the polar cap region is only so high as is observed (< 4 x 10~6K). Someother mechanisms are required.

关键词： pulsar: general gamma rays magnetic fields

How Fast Could a Proto-pulsar Rotate?

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Chinese Journal of astronomy and Astrophysics 2002年第6期2卷 533-538页

作者： ren-xin Xu, Hong-Guang Wang and Guo-Jun QiaoDepartment of astronomy, school of physics, peking university, beijing 100871 Department of astronomy School of Physics Peking University Beijing 100871

According to two estimated relations between the initial period and the dynamo-generated magnetic dipole field of pulsars, we calculate the statistical distributions of pulsar initial periods. It is found that proto-pulsars are very likely to have rotation periods between 20 ms and 30 ms, and that most of the pulsars rotate initially at a period < 60 ms. Our result supports the asymmetric neutrino emission model for pulsar kick.

关键词： pulsars neutron stars magnetic fields

Inclination of Broad Line Region in Narrow Line and Broad Line Seyfert 1 Galaxies

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Chinese Journal of astronomy and Astrophysics 2002年第6期2卷 487-500页

作者： Tian-Zhi Zhang and Xue-Bing WuDepartment of astronomy, school of physics, peking university, beijing 100871 Department of astronomy School of Physics Peking University Beijing 100871

The sizes of the Broad Line Region (BLR) of some Seyfert 1 galaxies and nearby quasars can be determined by the reverberation mapping method. Combining with the observed FWHM of Hbeta emission line and assuming that the motion of BLR clouds is virialized, the black hole masses of these objects have been estimated. However, this method strongly depends on the poorly-understood geometry and inclination of the BLR. On the other hand, a tight correlation between the black hole mass and the bulge velocity dispersion was recently found for both active and nearby inactive galaxies. This may provide another method, independent of the BLR geometry, for estimating the black hole mass. Using this method for estimating the black hole mass and combining with the measured BLR size and FWHM of Hbeta emission line, we derived the BLR inclination angles for 20 Seyfert 1 galaxies under the assumption that the BLR is disk-like. The derived inclination angles agree well with those derived previously by fitting the UV continuum and Hbeta emission line profiles. Adopting a relation between the FWHMs of [OIII]lambda5007 forbidden line and the stellar velocity dispersion, we also estimated the BLR inclinations for 50 narrow line Seyfert 1 galaxies (NLS1s). We found that the inclinations of broad Line Seyfert 1 galaxies (BLS1s) axe systematically greater than those of NLS1s, which seldom exceed 30degrees. This may be an important factor that leads to the differences between NLS1s and BLS1s if the BLR of NLS1s is really disk-like.

关键词： galaxies : active galaxies : nuclei galaxies : Seyfert

Abrupt climate change and collapse of ancient civilizations at 2200BC-2000BC

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Progress in Natural Science:Materials International 2005年第10期15卷 46-52页

作者： WANG Shaowu (Department of Atmospheric Science, school of physics, peking university, beijing 100871, China) Department of Atmospheric Science School of Physics Peking University Beijing 100871 China

Plentiful evidence of historical, archaeological and palaeoclimatic studies proved that an abrupt change from wetter to drier climate occurred over the Nile Valley,the Mesopotamia, the Indus Valley and Huanghe River Valley at 2200BC-2000BC. The abrupt change was developed based on the general lowering of temperature in the middle latitudes, and was a strong cold event since the beginning of the Megathermal (8.5-3.0 kaBP). Collapse of Nile civilization appeared at the First Intermediate Period (2181BC-2040BC). Civilization of Mesopotamia began collapse following the disintegration of Akkadian Empire. This process lasted to the foundation of Babylon Kingdom from 2200BC to 1900BC. Indus civilization abruptly fell off at 1800BC. A widespread alternation of archaeological cultures happened in China at ca. 2000BC except only in its central part. Longsheng culture was replaced by the Erlitou culture, which is now acknowledged in China as Xia Culture. Foundation of Xia Dynasty at 2070BC opened a new chapter in the development of Chinese civilization. Studies indicated that abrupt climate change may be caused by the weakening of the Thermohaline Circulation (THC).

关键词： 2200BC-2000BC abrupt climate change collapse of ancient civilization.

|m| Partial wave treatment for two-dimensional Coulomb-scattering and Regge pole

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Science China(physics,Mechanics & astronomy) 2004年第6期47卷 676-684页

作者： WANG Jing & ZENG Jinyan Department of physics,Tsinghua university,beijing 100084,China school of physics,peking university,beijing 100871,China Department of physics Tsinghua University Beijing 100084 China school of physics Peking University Beijing 100871 China

The symmetry and |m| partial-wave analysis for two-dimensional (2D) Coulomb-scattering is investigated. As a function of energyE, the |m| partial-wave scattering amplitudef |m|(θ) is analytically continuated to the, negativeE (complexk) plane, and it is found that the bound state energy eigenvalues (E<0) are just located at the poles off |m|(θ) on the positive imaginaryk axis as is expected. In addition, as a function of |m|,f |m|(θ) is analytically continuated to the complex |m| plane, the bound state energy eigenvalues are just located at the poles off |m|(θ) on the positive real |m| axis.

关键词： two-dimensional Coulomb scattering, |m| partial-wave, Regge pole.

Genetic and logic networks with the signal-inhibitor-activator structure are dynamically robust

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Progress in Natural Science:Materials International 2006年第12期16卷 1329-1336页

作者： LI Fangting** and TAN Ning(school of physics and Centre for Theoretical Biology, peking university, beijing 100871, China) [a]school of physics and Centre for Theoritical Biology Peking University Beijing China

The proteins, DNA and RNA interaction networks govern various biological functions in living cells, these networks should be dynamically robust in the intracellular and environmental fluctuations. Here, we use Boolean network to study the robust structure of both genetic and logic networks. First, SOS network in bacteria E. coli, which regulates cell survival and repair after DNA damage, is shown to be dynamically robust. Comparing with cell cycle network in budding yeast and flagella network in E. coli, we find the signal-inhibitor-activator (SIA) structure in transcription regulatory networks. Second, under the dynamical rule that inhibition is much stronger than activation, we have searched 3-node non-self-loop logical networks that are dynamically robust, and that if the attractive basin of a final attractor is as large as seven, and the final attractor has only one active node, then the active node acts as inhibitor, and the SIA and signal-inhibitor (SI) structures are fundamental architectures of robust networks. SIA and SI networks with dynamic robustness against environment uncertainties may be selected and maintained over the course of evolution, rather than blind trial-error testing and being an accidental consequence of particular evolutionary history. SIA network can perform a more complex process than SI network, and SIA might be used to design robust artificial genetic network. Our results provide dynamical support for why the inhibitors and SIA/SI structures are frequently employed in cellular regulatory networks.

关键词： genetic network signal-inhibitor-activator (SIA) structure Boolean network model dynamical robust.

Relationship between the tropical cyclone genesis over the Northwest Pacific and the sea surface temperature anomalies

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Progress in Natural Science:Materials International 2007年第10期17卷 1208-1212页

作者： Wang Jinbo, Qian Weihong and Zhang xin(Monsoon and Environment Research Group, school of physics, peking university, beijing 100871, China) Monsoon and Environment Research Group School of Physics Peking University Beijing 100871 China

Using the tropical cyclone (TC) data derived from the Joint Typhoon Warning Center (JTWC) and the sea surface temperature data derived from the Joint Environmental Data Analysis Center (JEDAC) at the Scripps Institute of Oceanography from January 1955 to December 2000, we analyzed the relationship between the TC genesis over the Northwest Pacific (NWP) and the sea surface temperature anomalies (SSTA) over the Pacific basin. A long-term trend indicated that the highest frequency of monthly TC genesis appeared earlier and the annual genesis sum increased gradually during the last half century with some oscillations. No significant synchronous correlation was found between the NWP TC events and the SSTA over the Pacific basin, while the annual sum of TC genesis was closely related with the SSTA averaged from the first three months (January, February and March) of the year in the equatorial western and eastern Pacific and over mid-high latitudes of the North Pacific. The results implied that there are an interannual El Nio SSTA mode in the equatorial western and eastern Pacific and an interdecadal SSTA mode in the northern Pacific, which affected the TC genesis. A regression analysis between the first three-month SSTA and the annual TC sum based on two time scales was conducted. The correlation coefficient between simulated and observed TC sums reached a high value of 0.77.

关键词： tropical cyclone long-term trend sea surface temperature Pacific.

Signal propagations and linkages of subsurface temperature anomalies in the tropical Pacific and Indian Ocean

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Progress in Natural Science:Materials International 2005年第9期15卷 804-809页

作者： QIAN Weihong** and HU Haoran(Monsoon & Environment Research Group, school of physics, peking university, beijing 100871, China) Monsoon & Environment Research Group School of Physics Peking University Beijing 100871 China

The propagation characteristics of signals along different zonal-time profiles are analyzed using surface and subsurface temperature anomalies over the tropical Pacific and Indian oceans. Analyses show that there are intrinsic relationships between El Nio events in the eastern equatorial Pacific and dipole events in the equatorial Indian Ocean. In the region of tropical North Pacific between the equator and 16°N, there is a circle of propagation of subsurface temperature anomalies. El Nio events only happen when the warm subsurface signals reach the eastern equatorial Pacific. Dipole events are characterized when a warm subsurface signal travels along off-equatorial Indian Ocean to the western boundary. From these analyses, we believe that subsurface temperature anomalies can be considered to be the oceanographic early signal to forecast El Nio events in Pacific Ocean and dipole events in Indian Ocean, respectively.

关键词： El Nio event dipole event subsurface sea temperature early signal.

THE PHYSICAL ENTROPY OF SINGLE CONSERVATION LAWS

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Journal of Computational Mathematics 1998年第5期16卷 437-444页

作者： (Department of Mathematics, peking university, beijing 100871, China) beijing Univ Dept Math Beijing 100871 Peoples R China

By means of the comparisons with the formulas in statistical mechanics and thermodynamics, in this paper it is demonstrated that for the single conservation law partial derivative(t)u + partial derivative(x)f(u) = 0, if the flux function f(u) is convex (or concave), then, the physical entropy is S = -f(u); Furthermore, if we assume this result can be generalized to any f(u) with two order continuous derivative, from the thermodynamical principle that the local entropy production must be non-negative, one entropy inequality is derived, by which the O.A. Olejnik's famous E- condition can be explained successfully in physics.

关键词： conservation laws entropy entropy production