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Avoided crossings between non-radial modes in low mass RGB stars

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Research in Astronomy and Astrophysics 2012年第12期12卷 1655-1665页

作者： Jun-Jun Guo1,2,3,Yan Li1,2 and Xiang-Jun Lai1,2 1 National Astronomical Observatories/Yunnan Observatory,chinese academy of sciences, kunming 650011,china 2 key laboratory for the structure and evolution of celestial objects,chinese academy of sciences,kunming 650011,china 3 Graduate University of chinese academy of sciences,Beijing 100049,china National Astronomical Observatories/Yunnan Observatory Chinese Academy of Sciences Kunming 650011 China key laboratory for the structure and evolution of celestial objects Chinese Academy of Sciences Kunming 650011 China Graduate University of chinese academy of sciences Beijing 100049 China

Non-radial p modes and g modes appear simultaneously in red giant stars. Their frequencies have different variation rates,causing their frequencies to become close during stellar evolution so that avoided crossings *** separation between regions where acoustic waves and gravity waves propagate for l=1,2 and 3 is different,which results in the coupling efficiency also being *** present the results of numerical computations of the models we *** find that the two kinds of modes for l=2 and 3 need to be closer in frequency in order for a complete exchange to occur,compared to the case for modes with l=*** scaled oscillation frequencies also present better regularity with evolution than modes with l=1. In order to study the effect of the avoided crossings in detail,we set the mode which has the smallest mode inertia to be the p *** plot the two kinds of modes for l =1,2 and 3 in frequency and periodéchelle diagrams and find modes of l=2 and 3 fit the two relations better;they are more equally spaced in frequency and period than modes with l=*** careful observation of the two kinds oféchelle diagrams for l=2 and 3,we still find that some p modes shift a little from being equally spaced in frequency and some g modes,which are close to those p modes in period,shift a little from being equally spaced in ***,we study the relation between the deviation from period being equally spaced and the mode inertia of g modes for different *** g modes of l=1 with a period closer to the p mode have less inertia and the deviation is bigger in the periodéchelle *** deviation is also obvious. However g modes of l=2 and 3 shift a little or have almost no deviation from being equally spaced in period,even though some of them may have strong coupling and close mode inertia like in the p ***,we suggest a possible method for measuring period spacing of g modes precisely using mixed g modes with l=2 and 3 that have fewer observed mixed g m

关键词： stars:oscillations-stars:red giants

Birthrates and delay times of Type Ia supernovae

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Science china(Physics,Mechanics & Astronomy) 2010年第3期53卷 586-590页

作者： WANG Bo1,2,3, LIU ZhengWei1,2,3, HAN YunKun1,2,3, LEI ZhenXin1,2,3, LUO YangPing1,2,3 & HAN ZhanWen1,2 1National Astronomical Observatories/Yunnan Observatory, chinese academy of sciences, kunming 650011, china 2key laboratory for the structure and evolution of celestial objects, chinese academy of sciences, kunming 650011, china 3Graduate University of chinese academy of sciences, Beijing 100049, china National Astronomical Observatories/Yunnan Observatory Chinese Academy of Sciences Kunming China key laboratory for the structure and evolution of celestial objects Chinese Academy of Sciences Kunming China Graduate University of chinese academy of sciences Beijing China

Type Ia supernovae (SNe Ia) play an important role in diverse areas of astrophysics, from the chemical evolution of galaxies to observational cosmology. However, the nature of the progenitors of SNe Ia is still unclear. In this paper, according to a detailed binary population synthesis study, we obtained SN Ia birthrates and delay times from different progenitor models, and compared them with observations. We find that the Galactic SN Ia birthrate from the double-degenerate (DD) model is close to those inferred from observations, while the birthrate from the single-degenerate (SD) model accounts for only about 1/2-2/3 of the observations. If a single starburst is assumed, the distribution of the delay times of SNe Ia from the SD model is a weak bimodality, where the WD + He channel contributes to the SNe Ia with delay times shorter than 100 Myr, and the WD + MS and WD + RG channels to those with age longer than 1 Gyr.

关键词： binaries: close stars: evolution supernovae: general white dwarfs

A statistical study of the relation between soft X-ray excess and accretion disk

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Science china(Physics,Mechanics & Astronomy) 2010年第S1期53卷 102-105页

作者： LIU JieYing1,2,3 & QIAO ErLin1,2 1 National Astronomical Observatories/Yunnan Observatory,chinese academy of Science,kunming 650011,china 2 key laboratory for the structure and evolution of celestial objects,chinese academy of sciences,kunming 650011,china 3 Graduate University of chinese academy of sciences,Beijing 100049,china National Astronomical Observatories/Yunnan Observatory Chinese Academy of Science Kunming China key laboratory for the structure and evolution of celestial objects Chinese Academy of Sciences Kunming China Graduate University of chinese academy of sciences Beijing China

To study the origin of the soft X-ray excess,we compile a sample of 94 unobscured,radio-quiet QSOs and Seyfert galaxies with available data from GALEX and *** find that 50 sources show strong soft X-ray excess and the other 44 show weak/no soft X-ray *** analyses of the data indicate that the difference in soft X-rays is mainly but not only resulting from different accretion rates(in units of Eddington rate).The statistical study of the sources with soft X-ray excess shows that the strength of soft X-ray excess weakly and positively correlates with the Eddington ratio and increases with the increase of the strength of UV radiations relative to the *** that the UV emissions are from the thin disk,the correlations imply that the origin of soft X-ray excess is associated with the thin disk,either by means of Comptonization of the disk photons or in some other ways.

关键词： accretion:accretion disks ultraviolet:galaxies X-rays:galaxies

Multi-epoch X-ray observations of the narrow-line Seyfert 1 galaxy SDSS J160508.87+323921.4 with XMM-Newton

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Science china(Physics,Mechanics & Astronomy) 2010年第S1期53卷 207-211页

作者： AI YanLi1,2,3,YUAN WeiMin1,2,ZHOU HongYan4,5 & WANG JianGuo1,2,3 1 National Astronomical Observatories/Yunnan Observatory,chinese academy of sciences,kunming 650011,china 2 key laboratory for the structure and evolution of celestial objects,chinese academy of sciences,kunming 650011,china 3 Graduate University of the chinese academy of sciences,Beijing 100049,china 4 Center for Astrophysics,University of Science and Technology of china,Hefei 230026,china 5 Joint Institute of Galaxies and Cosmology,SHAO and USTC,Shanghai 200030,china National Astronomical Observatories/Yunnan Observatory Chinese Academy of Sciences Kunming China key laboratory for the structure and evolution of celestial objects Chinese Academy of Sciences Kunming China Graduate University of the chinese academy of sciences Beijing China Center for Astrophysics University of Science and Technology of China Hefei China Joint Institute of Galaxies and Cosmology SHAO and USTC Shanghai China

We present results of multi-epoch XMM-Newton observations separated by several years of the narrow-line Seyfert 1(NLS1) galaxy,SDSS J160508.87+*** NLS1 showed X-ray flux variations on timescales of years as well as low amplitude variations on timescales as short as hours,while the X-ray spectral shape remained essentially *** spectrum shows a significant soft X-ray *** model of reflection from an ionized disc,that is dominant in the whole XMM-Newton bandpass,provides the best description of the observed spectra for all the observations,though alternatives such as Compton scattering(T-0.25 keV) cannot be ruled out in a statistical *** the disc reflection model,the observed variations may originate either from the change in the reflection fraction,or from the variability of the intrinsic X-ray luminosity.

关键词： galaxies:active Seyfert X-rays individual

Phylogeny of fireflies (Coleoptera: Lampyridae) inferred from mitochondrial 16S ribosomal DNA, with references to morphological and ethological traits

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Progress in Natural Science:Materials International 2006年第8期16卷 817-826页

作者： LI Xueyan, YANG Shuang, XIE Meng and LIANG Xingcai (laboratory of Entomology, kunming Institute of Zoology, chinese academy of sciences, kunming 650223, china key laboratory of Cellular and Molecular evolution, kunming Institute of Zoology, chinese academy of sciences, kunming 650223, china Graduate School of the chinese academy of sciences, Beijing 100039, china) laboratory of Entomology kunming Institute of Zoology chinese academy of sciences Kunming 650223 China Graduate School of the chinese academy of sciences Beijing 100039 China key laboratory of Cellular and Molecular evolution kunming Institute of Zoology Chinese Academy of Sciences Kunming 650223 China

We sequenced partial mitochondrial 16S ribosomal DNA (16S rDNA) of 18 firefly species from Southwest of china. Combined with homologous sequences previously reported, phylogenetic trees including Japanese, Korean and chinese species were reconstructed by neighbor-joining, maximum parsimony and Bayesian methods. All reconstructions agree on most nodes of the trees. Monophyly of Lampyridae is not supported because Rhagophthalmus ohbai in Rhagophthalmidae is included within it. Lamprigera, a genus placed unreliably in Lampyrinae, shows a close relationship to Amydetinae. Monophyly of Luciolinae is not supported because Pristolycus sagulatus (Lampyrinae) is included within it. In the Luciolinae, monophyly of Curtos and Hotaria is well established, respectively, but both morphological and molecular data continue to indicate that Luciola is not monophyletic and its subdivision is indeed necessary. Within the Lampyrinae, both Pyrocoelia and Diaphanes are not monophyletic, but monophyly of Pyrocoelia + Diaphanes is well supported. Phylogeny of Diaphanes is discussed for the first time. Generic placement of a newly discovered species (Diaphanes pectinealis Li et Liang) sharing some characters of Pyrocoelia and Diaphanes challenges the delimitation of these two similar genera. With references to the firefly mating systems, we suggest that more emphases should be placed on those sexually selected characters such as antennal structure in taxonomy of Lampyridae.

关键词： Lampyridae mitochondrial 16S rDNA morphological and ethological traits phylogeny.

Low genetic diversity and high genetic differentiation in the critically endangered Omphalogramma souliei (Primulaceae):implications for its conservation

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Journal of Systematics and evolution 2009年第2期47卷 103-109页

作者： Yuan HUANG Chang-Qin ZHANG De-Zhu LI(key laboratory of Biodiversity and Biogeography,kunming Institute of Botany,chinese academy of sciences,kunming 650204,china) key laboratory of Biodiversity and Biogeography Kunming Institute of Botany Chinese Academy of Sciences Kunming 650204 China

Omphalogramma souliei *** an endangered perennial herb only distributed in alpine areas of SW *** markers were applied to determine the genetic variation and genetic structure of 60 individuals of three populations of *** in NW Yunnan,*** genetic diversity at the species level is low with P= 42.5%(percentage of polymorphic bands) and Hsp=0.1762(total genetic diversity).However,a high level of genetic differentiation among populations was detected based on different measures(Nei’s genetic diversity analysis:Gst=0.6038;AMOVA analysis:Fst=0.6797).Low level of genetic diversity within populations and significant genetic differentiation among populations might be due to the mixed mating system in which xenog-amy predominated and autogamy played an assistant role in *** genetic drift due to small population size and limited current gene flow also resulted in significant genetic *** assessment of genetic variation and differentiation of the endangered species provides important information for conservation on a genetic *** strategies for this rare endemic species are proposed.

关键词： genetic differentiation genetic diversity ISSR markers mating system Omphalogramma souliei

Progress and development in thermodynamic theory of friction and wear

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Science china(Technological sciences) 2009年第4期52卷 844-849页

作者： DAI ZhenDong1 & XUE QunJi2 1 Institute of Bio-inspired structure and Surface Engineering, Nanjing University of Aeronautics and Astronautics, Nanjing 210016, china 2 State key laboratory of Solid Lubrication, chinese academy of sciences, Lanzhou 710000, china Institute of Bio-inspired structure and Surface Engineering Nanjing University of Aeronautics and Astronautics Nanjing China State key laboratory of Solid Lubrication Chinese Academy of Sciences Lanzhou China

Tribology theory lags well behind engineering needs because of those complex and multi-dimensional characteristics associated with friction and wear. The mechanism of friction is reviewed and discussed from a static thermodynamics perspective; research methods on the process of friction and wear and thermodynamic studies within the field of tribology are also reviewed. We propose that entropy can be a critical parameter in describing the evolution of friction and wear, and the entropy balance equation could be considered as a fundamental cornerstone for a systematic tribology theory. Applications of irreversible thermodynamic theory of tribology to various fields are reviewed.

关键词： friction and wear irreversible thermodynamics entropy generation multi-factor coupling

Allopatric divergence and regional range expansion of Juniperus sabina in china

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Journal of Systematics and evolution 2010年第3期48卷 153-160页

作者： 1Yu-Peng GUO 1Ru ZHANG 1Cui-Yun CHEN 2Dang-Wei ZHOU 1Jian-Quan LIU 1(Division of Molecular Ecology,key laboratory of Arid and Grassland Ecology,School of Life sciences,Lanzhou University,Lanzhou 730000,china) 2(key laboratory of Adaptation and evolution of Plateau Biota,Northwest Institute of Plateau Biology,chinese academy of sciences,Xining 810000,china) (Division of Molecular Ecology Key Laboratory of Arid and Grassland Ecology School of Life Sciences Lanzhou University Lanzhou 730000 China) (key laboratory of Adaptation and evolution of Plateau Biota Northwest Institute of Plateau Biology Chinese Academy of Sciences Xining 810000 China)

In this study,we aimed to study the phylogeographic pattern of Juniperus sabina,a shrub species commonly occurring in the northern,northwestern and western china. We sequenced three chloroplast DNA fragments (trnL-trnF,trnS-trnG,and trnD-trnT) for 137 individuals from 16 populations of this species. Five chloroplast DNA chlorotypes (A,B,C,D,and E) were identified and they showed no overlapping distribution. The population subdivision is very high (GST=0.926,NST=0.980),suggesting a distinct phylogeographic structure (NST>GST,Pchina. However,within each region,the interpopulation differentiation is extremely low. These results as well as statistical tests suggested distinct allopatric differentiations between regional populations and independent glacial refugia for postglacial recolonization. The deserts that developed during the late Quaternary might have acted as effective barriers to promote genetic differentiation among these regions. However,the low diversity dominated by the single chlorotype within each fragmented region suggested that all current populations were derived from a common regional range expansion.

关键词： cpDNA genetic diversity Juniperus sabina phylogeography range expansion.

Functional evolutionary developmental biology (evo-devo) of morphological novelties in plants

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Journal of Systematics and evolution 2010年第2期48卷 94-101页

作者： Jisi ZHANG Ying TIAN Li WANG Chaoying HE (State key laboratory of Systematic and evolutionary Botany,Institute of Botany,chinese academy of sciences,Beijing 100093,china) (State key laboratory of Systematic and evolutionary Botany Institute of Botany Chinese Academy of Sciences Beijing 100093 China)

The origin of morphological and ecological novelties is a long-standing problem in evolutionary *** these processes requires investigation from both the development and evolution standpoints,which promotes a new research field called "evolutionary developmental biology" (evo-devo).The fundamental mechanism for the origin of a novel structure may involve heterotopy,heterochrony,ectopic expression,or loss of an existing regulatory ***,the morphological and ecological traits controlled by the regulatory genes may be gained,lost,or regained during *** morphological novelties,for example,include homeotic alterations (related to organ identity),symmetric diversity,and changes in the size and morphology of the floral *** gains and losses can potentially arise through modification of the existing regulatory ***,we review current knowledge concerning the origin of novel floral structures,such as "evolutionary homeotic mutated flowers",floral symmetry in various plant species,and inflated calyx syndrome (ICS) within *** evo-devo of the morphological novelties is a central theme of plant evolutionary *** addition,the discussion is extended to consider agronomic or domestication-related traits,including the type,size,and morphology of fruits (berries),within Solanaceae.

关键词： biodiversity development evolution functional evo-devo heterochrony heterotopy morphological novelty