The Large sky Area Multi-Object Fiber Spectroscopic Telescope（LAMOST） general survey is a spectroscopic survey that will eventually cover approximately half of the celestial sphere and collect 10 million spectra of ...The Large sky Area Multi-Object Fiber Spectroscopic Telescope（LAMOST） general survey is a spectroscopic survey that will eventually cover approximately half of the celestial sphere and collect 10 million spectra of stars, galaxies and QSOs. Objects in both the pilot survey and the first year regular survey are included in the LAMOST DR1. The pilot survey started in October 2011 and ended in June 2012, and the data have been released to the public as the LAMOST Pilot Data Release in August 2012. The regular survey started in September 2012, and completed its first year of operation in June 2013. The LAMOST DR1 includes a total of 1202 plates containing 2 955 336 spectra, of which 1 790 879 spectra have observed signalto-noise ratio（SNR） ≥ 10. All data with SNR ≥ 2 are formally released as LAMOST DR1 under the LAMOST data policy. This data release contains a total of 2 204 696 spectra, of which 1 944 329 are stellar spectra, 12 082 are galaxy spectra and 5017 are quasars. The DR1 not only includes spectra, but also three stellar catalogs with measured parameters： late A,FGK-type stars with high quality spectra（1 061 918 entries）, A-type stars（100 073 entries）, and M-type stars（121 522 entries）. This paper introduces the survey design, the observational and instrumental limitations, data reduction and analysis, and some caveats. A description of the FITS structure of spectral files and parameter catalogs is also provided.展开更多
We report the discovery of an extremely metal-poor（EMP） giant,LAMOST J110901.22＋075441.8, which exhibits a large excess of r-process elements with [Eu/Fe] ～ ＋1.16. The star is one of the newly discovered EMP star...We report the discovery of an extremely metal-poor（EMP） giant,LAMOST J110901.22＋075441.8, which exhibits a large excess of r-process elements with [Eu/Fe] ～ ＋1.16. The star is one of the newly discovered EMP stars identified from the LAMOST low-resolution spectroscopic survey and a highresolution follow-up observation with the Subaru Telescope. Stellar parameters and elemental abundances have been determined from the Subaru spectrum. Accurate abundances for a total of 23 elements including 11 neutron-capture elements from Sr through Dy have been derived for LAMOST J110901.22＋075441.8. The abundance pattern of LAMOST J110901.22＋075441.8 in the range of C through Zn is in line with the ＂normal＂ population of EMP halo stars, except that it shows a notable underabundance in carbon. The heavy element abundance pattern of LAMOST J110901.22＋075441.8 is in agreement with other well studied cool r-II metal-poor giants such as CS 22892-052 and CS 31082-001. The abundances of elements in the range from Ba through Dy match the scaled solar r-process pattern well.LAMOST J110901.22＋075441.8 provides the first detailed measurements of neutroncapture elements among r-II stars at such low metallicity with [Fe/H]-3.4, and exhibits similar behavior as other r-II stars in the abundance ratio of Zr/Eu as well as Sr/Eu and Ba/Eu.展开更多
This paper theoretically investigates the coherent phase control in electron-argon scattering assisted by a bichro- matic laser field. The laser field is composed of a fundamental component and its second harmonic. Th...This paper theoretically investigates the coherent phase control in electron-argon scattering assisted by a bichro- matic laser field. The laser field is composed of a fundamental component and its second harmonic. The incoming and out going states of electron are described by the Volkov wave functions, and the electron-target interaction is treated as a screening potential. Numerical results for differential cross section of multiphoton processes vs the phase difference between the two components of laser field are discussed for several scattering angles and impact energies.展开更多
The positron impact-ionisation of atomic hydrogen in the presence of a linearly polarised bichromatic field is investigated in the first Born approximation. The field is composed of a fundamental frequency and its sec...The positron impact-ionisation of atomic hydrogen in the presence of a linearly polarised bichromatic field is investigated in the first Born approximation. The field is composed of a fundamental frequency and its second harmonic. The state of positron in the field is described by the Volkov wavefunction, and the continuum state of the ejected electron is described by the Coulomb-Volkov wavefunction. The dressed ground state of target is a first order time-dependent perturbative wavefunction. The triple differential cross sections and their dependencies on laser field parameters are discussed and compared with the results modified by a monochromatic field. Numerical results show that the coherent phase control is significant and the laser-assisted ionisation cross sections caused by positron and electron are different.展开更多
As a counterexample of the Euler condition for nonholonomic constraint problems [H. C. Shen, Acta Phys. Sin. 54, 2468 （2005）], we investigate the Apell-Hamel dynamical system on a horizontally moving plate. The inco...As a counterexample of the Euler condition for nonholonomic constraint problems [H. C. Shen, Acta Phys. Sin. 54, 2468 （2005）], we investigate the Apell-Hamel dynamical system on a horizontally moving plate. The inconsistency of the results with Newton mechanics suggests that the Euler condition is not a universal model for nonlinear nonholonomic systems. This is attributed to the fact that the virtual displacements so obtained are not normal to the constraint forces.展开更多
We review recent developments in the use of magnetic lattices as a complementary tool to optical lattices for trapping periodic arrays of ultracold atoms and degenerate quantum gases. Recent advances include the reali...We review recent developments in the use of magnetic lattices as a complementary tool to optical lattices for trapping periodic arrays of ultracold atoms and degenerate quantum gases. Recent advances include the realisation of Bose–Einstein condensation in multiple sites of a magnetic lattice of one-dimensional microtraps, the trapping of ultracold atoms in square and triangular magnetic lattices,and the fabrication of magnetic lattice structures with submicron period suitable for quantum tunnelling experiments.Finally, we describe a proposal to utilise long-range interacting Rydberg atoms in a large spacing magnetic lattice to create interactions between atoms on neighbouring sites.展开更多
This paper is dedicated to the study of viscous compressible barotropic fluids in dimension N 2.We address the question of well-posedness for large data having critical Besov regularity.Our result improves the analysi...This paper is dedicated to the study of viscous compressible barotropic fluids in dimension N 2.We address the question of well-posedness for large data having critical Besov regularity.Our result improves the analysis of Danchin and of the author inasmuch as we may take initial density in B N p p,1 with 1 p < +∞.Our result relies on a new a priori estimate for the velocity,where we introduce a new unknown called effective velocity to weaken one of the couplings between the density and the velocity.In particular,our result is the first in which we obtain uniqueness without imposing hypothesis on the gradient of the density.展开更多
基金funded by the National Basic Research Program of China (973 Program, 2014CB845700)the National Natural Science Foundation of China (Grant Nos. 11390371)Funding for the project has been provided by the National Development and Reform Commission
文摘The Large sky Area Multi-Object Fiber Spectroscopic Telescope（LAMOST） general survey is a spectroscopic survey that will eventually cover approximately half of the celestial sphere and collect 10 million spectra of stars, galaxies and QSOs. Objects in both the pilot survey and the first year regular survey are included in the LAMOST DR1. The pilot survey started in October 2011 and ended in June 2012, and the data have been released to the public as the LAMOST Pilot Data Release in August 2012. The regular survey started in September 2012, and completed its first year of operation in June 2013. The LAMOST DR1 includes a total of 1202 plates containing 2 955 336 spectra, of which 1 790 879 spectra have observed signalto-noise ratio（SNR） ≥ 10. All data with SNR ≥ 2 are formally released as LAMOST DR1 under the LAMOST data policy. This data release contains a total of 2 204 696 spectra, of which 1 944 329 are stellar spectra, 12 082 are galaxy spectra and 5017 are quasars. The DR1 not only includes spectra, but also three stellar catalogs with measured parameters： late A,FGK-type stars with high quality spectra（1 061 918 entries）, A-type stars（100 073 entries）, and M-type stars（121 522 entries）. This paper introduces the survey design, the observational and instrumental limitations, data reduction and analysis, and some caveats. A description of the FITS structure of spectral files and parameter catalogs is also provided.
基金the paper.H.N.L.and G.Z.acknowledge supports by the National Natural Science Foundation of China (Grant Nos.11103030, 11233004 and 11390371)W.A.and T.S.are supported by the JSPS Grant-in-Aid for Scientific Research (S: 23224004)+1 种基金S.H.is supported by the JSPS Grant-in-Aid for Scientific Research (c:26400231)N.C.acknowledges support from Sonderforschungsbereich 881 "The Milky Way System" (subproject A4) of the German Research Foundation (DFG)
文摘We report the discovery of an extremely metal-poor（EMP） giant,LAMOST J110901.22＋075441.8, which exhibits a large excess of r-process elements with [Eu/Fe] ～ ＋1.16. The star is one of the newly discovered EMP stars identified from the LAMOST low-resolution spectroscopic survey and a highresolution follow-up observation with the Subaru Telescope. Stellar parameters and elemental abundances have been determined from the Subaru spectrum. Accurate abundances for a total of 23 elements including 11 neutron-capture elements from Sr through Dy have been derived for LAMOST J110901.22＋075441.8. The abundance pattern of LAMOST J110901.22＋075441.8 in the range of C through Zn is in line with the ＂normal＂ population of EMP halo stars, except that it shows a notable underabundance in carbon. The heavy element abundance pattern of LAMOST J110901.22＋075441.8 is in agreement with other well studied cool r-II metal-poor giants such as CS 22892-052 and CS 31082-001. The abundances of elements in the range from Ba through Dy match the scaled solar r-process pattern well.LAMOST J110901.22＋075441.8 provides the first detailed measurements of neutroncapture elements among r-II stars at such low metallicity with [Fe/H]-3.4, and exhibits similar behavior as other r-II stars in the abundance ratio of Zr/Eu as well as Sr/Eu and Ba/Eu.
基金This research was funded by grants from the Spanish Ministeriode Ciencia(No.PM-1999-23 and BMC-2001-1299)This research was funded by grants from Fundacion Mutua Madrilea Automovilista
基金Project supported by the National Natural Science Foundation of China (Grant Nos. 10874169 and 10674125)the National Basic Research Program of China (Grant No. 2007CB925200)S.-M. Li is grateful to Deutscher Akademischer Austauschdienst and Deutsche Forschungsgemeinschaft for financial support during his stay in Germany
文摘This paper theoretically investigates the coherent phase control in electron-argon scattering assisted by a bichro- matic laser field. The laser field is composed of a fundamental component and its second harmonic. The incoming and out going states of electron are described by the Volkov wave functions, and the electron-target interaction is treated as a screening potential. Numerical results for differential cross section of multiphoton processes vs the phase difference between the two components of laser field are discussed for several scattering angles and impact energies.
基金Project supported by the National Natural Science Foundation of China (Grant Nos. 10874169 and 10674125)the National Basic Research Program of China (Grant Nos. 2007CB925200 and 2010CB923301)the Deutsche Forschungsgemeinschaft for the support (Contract No. 446CHV113/261/0-1) during his stay in Germany
文摘The positron impact-ionisation of atomic hydrogen in the presence of a linearly polarised bichromatic field is investigated in the first Born approximation. The field is composed of a fundamental frequency and its second harmonic. The state of positron in the field is described by the Volkov wavefunction, and the continuum state of the ejected electron is described by the Coulomb-Volkov wavefunction. The dressed ground state of target is a first order time-dependent perturbative wavefunction. The triple differential cross sections and their dependencies on laser field parameters are discussed and compared with the results modified by a monochromatic field. Numerical results show that the coherent phase control is significant and the laser-assisted ionisation cross sections caused by positron and electron are different.
基金supported by the National Natural Science Foundation of China (Grant Nos 10874169 and 10674125)and the National Basic Research Program of China (Grant No 2007CB925200)Li Shu-Min is grateful to DAAD and DFG for financial supportduring his stay in Germany
文摘As a counterexample of the Euler condition for nonholonomic constraint problems [H. C. Shen, Acta Phys. Sin. 54, 2468 （2005）], we investigate the Apell-Hamel dynamical system on a horizontally moving plate. The inconsistency of the results with Newton mechanics suggests that the Euler condition is not a universal model for nonlinear nonholonomic systems. This is attributed to the fact that the virtual displacements so obtained are not normal to the constraint forces.
基金supported by an Australian Research Council Discovery Project Grant(DP130101160)
文摘We review recent developments in the use of magnetic lattices as a complementary tool to optical lattices for trapping periodic arrays of ultracold atoms and degenerate quantum gases. Recent advances include the realisation of Bose–Einstein condensation in multiple sites of a magnetic lattice of one-dimensional microtraps, the trapping of ultracold atoms in square and triangular magnetic lattices,and the fabrication of magnetic lattice structures with submicron period suitable for quantum tunnelling experiments.Finally, we describe a proposal to utilise long-range interacting Rydberg atoms in a large spacing magnetic lattice to create interactions between atoms on neighbouring sites.
文摘This paper is dedicated to the study of viscous compressible barotropic fluids in dimension N 2.We address the question of well-posedness for large data having critical Besov regularity.Our result improves the analysis of Danchin and of the author inasmuch as we may take initial density in B N p p,1 with 1 p < +∞.Our result relies on a new a priori estimate for the velocity,where we introduce a new unknown called effective velocity to weaken one of the couplings between the density and the velocity.In particular,our result is the first in which we obtain uniqueness without imposing hypothesis on the gradient of the density.
