Impacts of Restructurings on Manufacturing Productive Efficiency: Evidence from China

This paper studies the effects of privatization and non-ownership-change reforms on firms’ productivity in China. As one of the most prominent empirical challenges in China privatization studies, endogeneity problems are addressed with a first-difference instrumental variable GMM estimation. We find that privatization does not improve firms’ productivity immediately. Instead, its effects become significantly positive in the year after conversion. In addition, partial privatization fails to lead to improved efficiency whereas insider privatization boosts firms’ productivity shortly after the first year of privatization but the effects quickly fade after two years of privatization. Lastly, all non-ownership-change reforms, except leasing, are proved to be ineffective even when issues like social burdens, worker redundancy, management incentives and soft-budget constraint are tackled before the restructuring.privatization, soft budget constraint, transition economies, Chinese economy

Privatization, Soft Budget Constraint, and Social Burdens: A Random-Effects Stochastic Frontier Analysis on Chinese Manufacturing Technical Efficiency

Traditional panel stochastic frontier studies on privatization of Chinese State-owned firms face a major challenge, namely, the endogeneity problem. The endogeneity problem is present because decision-making process of privatization in China is very likely influenced by some unobserved characteristics of a firm. In particular, better-performing SOEs are more likely to be chosen for privatization because the local governments may have incentives to attract private investors or to retain momentum for future reform. To deal with this challenge, this paper proposes a two-step stochastic frontier model. The first step addresses the endogeneity issue by estimating the probability of privatization with a random effects probit model. The second step estimation investigates the causes of Chinese manufacturing’s inefficiency with a random-effects stochastic frontier model. The estimation results suggest that privatization, hardening budget constraint and reducing firms’ social obligations have significantly contributed to the improvements of firms’ efficiency. However, no evidence is found that more autonomy for managers and lower debt asset ratio may help improve firms’ efficiency.Panel data, random effects, technical efficiency, stochastic frontier, privatization, soft-budget constraint, managerial incentives, social burdens

Thermodynamics of Spin-1/2 AF-AF-F and F-F-AF Trimerized Quantum Heisenberg Chains

The magnetization process, the susceptibility and the specific heat of the spin-1/2 AF-AF-F and F-F-AF trimerized quantum Heisenberg chains have been investigated by means of the transfer matrix renormalization group (TMRG) technique as well as the modified spin-wave (MSW) theory. A magnetization plateau at $m=1/6$ for both trimerized chains is observed at low temperature. The susceptibility and the specific heat show various behaviors for different ferromagnetic and antiferromagnetic interactions and in different magnetic fields. The TMRG results of susceptibility and the specific heat can be nicely fitted by a linear superposition of double two-level systems, where two fitting equations are proposed. Three branch excitations, one gapless excitation and two gapful excitations, for both systems are found within the MSW theory. It is observed that the MSW theory captures the main characteristics of the thermodynamic behaviors at low temperatures. The TMRG results are also compared with the possible experimental data.Comment: 11 pages, 10 figure

Labelled tree graphs, Feynman diagrams and disk integrals

In this note, we introduce and study a new class of "half integrands" in Cachazo-He-Yuan (CHY) formula, which naturally generalize the so-called Parke-Taylor factors; these are dubbed Cayley functions as each of them corresponds to a labelled tree graph. The CHY formula with a Cayley function squared gives a sum of Feynman diagrams, and we represent it by a combinatoric polytope whose vertices correspond to Feynman diagrams. We provide a simple graphic rule to derive the polytope from a labelled tree graph, and classify such polytopes ranging from the associahedron to the permutohedron. Furthermore, we study the linear space of such half integrands and find (1) a nice formula reducing any Cayley function to a sum of Parke-Taylor factors in the Kleiss-Kuijf basis (2) a set of Cayley functions as a new basis of the space; each element has the remarkable property that its CHY formula with a given Parke-Taylor factor gives either a single Feynman diagram or zero. We also briefly discuss applications of Cayley functions and the new basis in certain disk integrals of superstring theory.Comment: 30+8 pages, many figures;typos fixe

Simultaneous Testing of Mean and Variance Structures in Nonlinear Time Series Models

This paper proposes a nonparametric simultaneous test for parametric specification of the conditional mean and variance functions in a time series regression model. The test is based on an empirical likelihood (EL) statistic that measures the goodness of fit between the parametric estimates and the nonparametric kernel estimates of the mean and variance functions. A unique feature of the test is its ability to distribute natural weights automatically between the mean and the variance components of the goodness of fit. To reduce the dependence of the test on a single pair of smoothing bandwidths, we construct an adaptive test by maximizing a standardized version of the empirical likelihood test statistic over a set of smoothing bandwidths. The test procedure is based on a bootstrap calibration to the distribution of the empirical likelihood test statistic. We demonstrate that the empirical likelihood test is able to distinguish local alternatives which are different from the null hypothesis at an optimal rate.Bootstrap, empirical likelihood, goodness{of{t test, kernel estimation, least squares empirical likelihood, rate-optimal test

Meson mass modification in strange hadronic matter

We investigate in stable strange hadronic matter (SHM) the modifica- tion of the masses of the scalar (sigma,sigma') and the vector (omega,phi) mesons. The baryon ground state is treated in the relativistic Hartree approximation in the nonlinear sigma-omega and linear sigma'- phi model. In stable SHM, the masses of all the mesons reveal considerable reduction due to large vacuum polarization contribution from the hyperons and small density dependent effects caused by larger binding. PACS: 21.65+f, 24.10J