3,059 research outputs found

    Why the manufacturing firms in developing countries can be competitive? The evidence of China

    Get PDF
    Based on the data of more than 95,000 Chinese manufacturing firms, this study explores the reasons for the recent surge of manufacturing exports from China. Contrary to common belief, neither unit labor cost nor Research and Development (R&D) investment has been a contributing factor to the export success of Chinese firms, even in hightechnology sectors. Although exportation of high-technology products has traditionally been dominated by foreign manufacturing firms, domestic firms have invested more heavily in R&D than their foreign counterparts. However, the major contributors to the increase in Chinese exports are product innovation, collaboration with foreign investors, and fierce domestic competition

    Quark Effects in the Gluon Condensate Contribution to the Scalar Glueball Correlation Function

    Full text link
    One-loop quark contributions to the dimension-four gluon condensate term in the operator product expansion (OPE) of the scalar glueball correlation function are calculated in the MS-bar scheme in the chiral limit of nfn_f quark flavours. The presence of quark effects is shown not to alter the cancellation of infrared (IR) singularities in the gluon condensate OPE coefficients. The dimension-four gluonic condensate term represents the leading power corrections to the scalar glueball correlator and, therein, the one-loop logarithmic contributions provide the most important condensate contribution to those QCD sum-rules independent of the low-energy theorem (the subtracted sum-rules).Comment: latex2e, 6 pages, 7 figures embedded in latex fil

    The transition of Chinese S&T institutes since 1980s: policy, performance and implication

    Get PDF
    In 1985 China began its reform on the Science & Technology (S&T) sector which was inherited from a planned economy. The reform over the past 20 years is deemed to be a decisive factor in China’s science and technology progress. The paper first argues that two fundamental tasks of China’s S&T sector reform are to enhance scientific productivity and strengthen the industry-academic relationships. Subsequently, the reform policies are outlined within three categories: 1) reforming the funding system, 2) improving R&D management 3) strengthening industry-academic relationships. The evolution of S&T institutes such as the Chinese Academy of Science is examined to provide micro-level evidence of policy impacts. The scientific output of China’s S&T sector did achieve the remarkable improvement in the reform period, but we also observe the rapidly growing investment from the governments flew into the sector. The evaluation of the performance of the reform needs to examine the scientific productivity of the sector. Therefore, we proceed to measure the scientific productivity of China’s S&T institutes based on the R&D input and output data in the aggregate and provincial level. The Polynomial Distributed Lag model is utilized to uncover the structure of the lag between R&D input and output. The findings based on the aggregate data and provincial data confirm that the scientific productivity of China’s S&T institutes has been decreasing since 1990s. These results call for the future actions that can contribute to enhancing the scientific productivity of China’s S&T institutes

    Self-Trapping, Quantum Tunneling and Decay Rates for a Bose Gas with Attractive Nonlocal Interaction

    Full text link
    We study the Bose-Einstein condensation for a cloud of 7^7Li atoms with attractive nonlocal (finite-range) interaction in a harmonic trap. In addition to the low-density metastable branch, that is present also in the case of local interaction, a new stable branch appears at higher densities. For a large number of atoms, the size of the cloud in the stable high-density branch is independent of the trap size and the atoms are in a macroscopic quantum self-trapped configuration. We analyze the macroscopic quantum tunneling between the low-density metastable branch and the high-density one by using the istanton technique. Moreover we consider the decay rate of the Bose condensate due to inelastic two- and three-body collisions.Comment: 5 pages, 4 figures, submitted to Phys. Rev.

    First Results from the KMOS Lens-Amplified Spectroscopic Survey (KLASS): Kinematics of Lensed Galaxies at Cosmic Noon

    Get PDF
    We present the first results of the KMOS Lens-Amplified Spectroscopic Survey (KLASS), a new ESO Very Large Telescope (VLT) large program, doing multi-object integral field spectroscopy of galaxies gravitationally lensed behind seven galaxy clusters selected from the HST Grism Lens-Amplified Survey from Space (GLASS). Using the power of the cluster magnification we are able to reveal the kinematic structure of 25 galaxies at 0.7z2.30.7 \lesssim z \lesssim 2.3, in four cluster fields, with stellar masses 8log(M/M)118 \lesssim \log{(M_\star/M_\odot)} \lesssim 11. This sample includes 5 sources at z>1z>1 with lower stellar masses than in any previous kinematic IFU surveys. Our sample displays a diversity in kinematic structure over this mass and redshift range. The majority of our kinematically resolved sample is rotationally supported, but with a lower ratio of rotational velocity to velocity dispersion than in the local universe, indicating the fraction of dynamically hot disks changes with cosmic time. We find no galaxies with stellar mass <3×109M<3 \times 10^9 M_\odot in our sample display regular ordered rotation. Using the enhanced spatial resolution from lensing, we resolve a lower number of dispersion dominated systems compared to field surveys, competitive with findings from surveys using adaptive optics. We find that the KMOS IFUs recover emission line flux from HST grism-selected objects more faithfully than slit spectrographs. With artificial slits we estimate slit spectrographs miss on average 60% of the total flux of emission lines, which decreases rapidly if the emission line is spatially offset from the continuum.Comment: Accepted for publication in Ap

    Microwave characteristics of liquid-crystal tunable capacitors

    Get PDF
    [[abstract]]This letter investigates the microwave characteristics of the liquid crystal tunable capacitors for the first time. With the dielectric anisotropy properties, the liquid crystal capacitors present very different characteristics compared to the semiconductor or MEMS tunable capacitors. A quality factor of 310 with a control voltage of 5 V was achieved at 4 GHz. A tuning range of 25.3% for the control voltages from 0 to 5 V was obtained at 5 GHz. The results demonstrate the potential applications of liquid crystals as dielectric materials for capacitors with high quality factors and wide tuning ranges at high frequencies, particularly suitable for the future flexible electronics with transparent substrates.[[fileno]]2030121010007[[department]]電機工程學

    Instability of a Bose-Einstein Condensate with Attractive Interaction

    Full text link
    We study the stability of a Bose-Einstein condensate of harmonically trapped atoms with negative scattering length, specifically lithium 7. Our method is to solve the time-dependent nonlinear Schrodinger equation numerically. For an isolated condensate, with no gain or loss, we find that the system is stable (apart from quantum tunneling) if the particle number N is less than a critical number N_c. For N > N_c, the system collapses to high-density clumps in a region near the center of the trap. The time for the onset of collapse is on the order of 1 trap period. Within numerical uncertainty, the results are consistent with the formation of a "black hole" of infinite density fluctuations, as predicted by Ueda and Huang. We obtain numerically N_c approximately 1251. We then include gain-loss mechanisms, i.e., the gain of atoms from a surrounding "thermal cloud", and the loss due to two- and three-body collisions. The number N now oscillates in a steady state, with a period of about 145 trap periods. We obtain N_c approximately 1260 as the maximum value in the oscillations.Comment: Email correspondence to [email protected] ; 18 pages and 9 EPS figures, using REVTeX and BoxedEPS macro

    Anisotropic thermally activated diffusion in percolation systems

    Full text link
    We present a study of static and frequency-dependent diffusion with anisotropic thermally activated transition rates in a two-dimensional bond percolation system. The approach accounts for temperature effects on diffusion coefficients in disordered anisotropic systems. Static diffusion shows an Arrhenius behavior for low temperatures with an activation energy given by the highest energy barrier of the system. From the frequency-dependent diffusion coefficients we calculate a characteristic frequency ωc1/tc\omega_{c}\sim 1/t_{c}, related to the time tct_c needed to overcome a characteristic barrier. We find that ωc\omega_c follows an Arrhenius behavior with different activation energies in each direction.Comment: 5 pages, 4 figure

    Glueball production in radiative J/psi, Upsilon decays

    Get PDF
    Using a bound-state model of weakly bound gluons for glueballs made of two gluons and a natural generalization of the perturbative QCD formalism for exclusive hadronic processes, we present results for glueball production in radiative J/psi, Upsilon decays into several possible glueball states, including L \not= 0 ones. We perform a detailed phenomenological analysis, presenting results for the more favored experimental candidates and for decay angular distributions.Comment: RevTeX4, 26 pages, 11 eps figure
    corecore