Theory of anomalous Hall effect in transition-metal pentatelluride ZrTe5\mathrm{ZrTe}_{5} and HfTe5\mathrm{HfTe}_{5}

The anomalous Hall effect has considerable impact on the progress of condensed matter physics and occurs in systems with time-reversal symmetry breaking. Here we theoretically investigate the anomalous Hall effect in nonmagnetic transition-metal pentatelluride $\mathrm{ZrTe_{5}}$ and $\mathrm{HfTe}_{5}$. In the presence of Zeeman splitting and Dirac mass, there is an intrinsic anomalous Hall conductivity induced by the Berry curvature in the semiclassical treatment. In a finite magnetic field, the anomalous Hall conductivity rapidly decays to zero for constant spin-splitting and vanishes for the magnetic-field-dependent Zeeman energy. A semiclassical formula is derived to depict the magnetic field dependence of the Hall conductivity, which is beneficial for experimental data analysis. Lastly, when the chemical potential is fixed in the magnetic field, a Hall conductivity plateau arises, which may account for the observed anomalous Hall effect in experiments.Comment: 11 pages, 6 figures, reference information is update

Constraints on Ho\v{r}ava-Lifshitz gravity from GRB 170817A

In this work we focus on a toy model: (3+1)-dimensional Ho\v{r}ava-Lifshitz gravity coupling with an anisotropic electromagnetic (EM) field which is generated through a Kaluza-Klein reduction of a (4+1)-dimensional Ho\v{r}ava-Lifshitz gravity. This model exhibits a remarkable feature that it has the same velocity for both gravitational and electromagnetic waves. This feature makes it possible to restrict the parameters of the theory from GRB 170817A. In this work we use this feature to discuss possible constraints on the parameter $\beta$ in the theory, by analyzing the possible Lorentz invariance violation effect of the GRB 170817A. This is achieved by analyzing potential time delay of gamma-ray photons in this event. It turns out that it places a stringent constraint on this parameter. In the most ideal case, it gives $|1-\sqrt{\beta}|<(10^{-19}-10^{-18})$.Comment: 21 pages, 2 tables. Accepted for publication in EPJ

Financial Barrier against Access to Diagnostic Procedures among Enteric Fever Suspects in Highly-endemic Areas of China

There is currently no public financial system that fully covers enteric fever suspects in China. This study aimed at documenting the level of access to definitive diagnostic procedures, especially haemoculture, for these patients and examining the effect of health insurance on access to such care. A hospital-based cross-sectional study was conducted in six counties of Yunnan province, using a structured questionnaire and data extraction from medical records. In total, 714 subjects were recruited. Chi-square test and logistic regression were employed for analysis of data. The majority of the subjects were young adults (52%) and farmers (55%) from low-income families (49%). Only 407 (57%) could afford haemoculture routinely advised by their doctors. Of these, 123 (30%) had haemoculture positive for Salmonella Typhi. After adjustment for income, not getting haemoculture was marginally associated with percentage of reimbursement from the insurance (p value for trend=0.047). Illiteracy was also an independent risk factor for this outcome. The poor coverage of haemoculture for patients suspected of having enteric fever in this endemic area was due to financial barrier. The current health-insurance system inadequately relieved the problem. Further financial reform to help patients suspected with enteric fever is required

Tetra­aqua­bis[2-(2,4-dichloro­phen­oxy)acetato]nickel(II)

In the title complex, [Ni(C8H5Cl2O3)2(H2O)4], the NiII atom (site symmetry ) adopts a slightly distorted NiO6 octa­hedral coordination. An intra­molecular O—H⋯O hydrogen bond helps to establish the conformation. In the crystal, further O—H⋯O hydrogen bonds link the mol­ecules

New progress of ranging technology at Wuhan Satellite Laser Ranging Station

A satellite laser ranging system with an accuracy of the level of centimeter has been successfully developed at the Institute of Seismology, State Seismological Bureau with the cooperation of the Institute of Geodesy and Geophysics, Chinese Academy of Science. With significant improvements on the base of the second generation SLR system developed in 1985, ranging accuracy of the new system has been upgraded from 15 cm to 3-4 cm. Measuring range has also been expanded, so that the ETALON satellite with an orbit height of 20,000 km launched by the former U.S.S.R. can now be tracked. Compared with the 2nd generation SLR system, the newly developed system has the following improvements. A Q modulated laser is replaced by a mode-locked YAG laser. The new device has a pulse width of 150 ps and a repetition rate of 1-4 pps. A quick response photomultiplier has been adopted as the receiver for echo; for example, the adoption of the MCP tube has obviously reduced the jitter error of the transit time and has improved the ranging accuracy. The whole system is controlled by an IBM PC/XT Computer to guide automatic tracking and measurement. It can carry out these functions for satellite orbit calculation, real-time tracking and adjusting, data acquisition and the preprocessed of observing data, etc. The automatization level and reliability of the observation have obviously improved