The 2010 spring drought reduced primary productivity in southwestern China

Many parts of the world experience frequent and severe droughts. Summer drought can significantly reduce primary productivity and carbon sequestration capacity. The impacts of spring droughts, however, have received much less attention. A severe and sustained spring drought occurred in southwestern China in 2010. Here we examine the influence of this spring drought on the primary productivity of terrestrial ecosystems using data on climate, vegetation greenness and productivity. We first assess the spatial extent, duration and severity of the drought using precipitation data and the Palmer drought severity index. We then examine the impacts of the drought on terrestrial ecosystems using satellite data for the period 2000–2010. Our results show that the spring drought substantially reduced the enhanced vegetation index (EVI) and gross primary productivity (GPP) during spring 2010 (March–May). Both EVI and GPP also substantially declined in the summer and did not fully recover from the drought stress until August. The drought reduced regional annual GPP and net primary productivity (NPP) in 2010 by 65 and 46 Tg C yr−1, respectively. Both annual GPP and NPP in 2010 were the lowest over the period 2000–2010. The negative effects of the drought on annual primary productivity were partly offset by the remarkably high productivity in August and September caused by the exceptionally wet conditions in late summer and early fall and the farming practices adopted to mitigate drought effects. Our results show that, like summer droughts, spring droughts can also have significant impacts on vegetation productivity and terrestrial carbon cycling

Occurrence Rates and Heating Effects of Tangential and Rotational Discontinuities as Obtained from Three-dimensional Simulation of Magnetohydrodynamic Turbulence

In solar wind, magnetohydrodynamic (MHD) discontinuities are ubiquitous and often found to be at the origin of turbulence intermittency. They may also play a key role in the turbulence dissipation and heating of the solar wind. The tangential (TD) and rotational (RD) discontinuities are the two most important types of discontinuities. Recently, the connection between turbulence intermittency and proton thermodynamics has been being investigated observationally. Here we present numerical results from three-dimensional MHD simulation with pressure anisotropy and define new methods to identify and to distinguish TDs and RDs. Three statistical results obtained about the relative occurrence rates and heating effects are highlighted: (1) RDs tend to take up the majority of the discontinuities along with time; (2) the thermal states embedding TDs tend to be associated with extreme plasma parameters or instabilities, while RDs do not; (3) TDs have a higher average T as well as perpendicular temperature $T_\perp$. The simulation shows that TDs and RDs evolve and contribute to solar wind heating differently. These results will inspire our understanding of the mechanisms that generate discontinuities and cause plasma heating.Comment: 5 Figures, Submitted to Astrophys. J. Lett., in the process of refereein

Formation of Rotational Discontinuities in Compressive three-dimensional MHD Turbulence

Measurements of solar wind turbulence reveal the ubiquity of discontinuities. In this study, we investigate how the discontinuities, especially rotational discontinuities (RDs), are formed in magnetohydrodynamic (MHD) turbulence. In a simulation of the decaying compressive three-dimensional (3-D) MHD turbulence with an imposed uniform background magnetic field, we detect RDs with sharp field rotations and little variations of magnetic field intensity as well as mass density. At the same time, in the de Hoffman-Teller (HT) frame, the plasma velocity is nearly in agreement with the Alfv\'{e}n speed, and is field-aligned on both sides of the discontinuity. We take one of the identified RDs to analyze in details its 3-D structure and temporal evolution. By checking the magnetic field and plasma parameters, we find that the identified RD evolves from the steepening of the Alfv\'{e}n wave with moderate amplitude, and that steepening is caused by the nonuniformity of the Alfv\'{e}n speed in the ambient turbulence.Comment: Five figures enclosed. Submitted to Astrophys. J., Under referrin

Studies on Time-Lag Effect of Corporate Performance Influenced by Competitive Strategy

Corporate performance has been analyzed by using quarterly economic data between 1st Quarter of 2003 and 1st Quarter of 2011 shown in the listing companies of the Chinese medical biologicals after implementing the formulated strategy. Studies show competitive strategy influenced corporate performance to some extent brings about time-lag effect and differentiation strategy influenced corporate performance related Duration of Lag inferior to that of Lowcost strategy; at the same time, competitive strategy has a long-term effect on corporate performance, with differentiation strategy influenced Duration of Lag in corporate performance which is more longer than that of Lowcost strategy. Finally, from test results we can also conclude that it is more difficult for implementing differentiation strategy than for Lowcost strategy, even bringing about highly risks and there is little possibility to succeed after being implemented.Key words: Differentiation strategy; Lowcost strategy; Coporate performance; Time-Lag effec

Doping-free complementary WSe2 circuit via van der Waals metal integration.

Two-dimensional (2D) semiconductors have attracted considerable attention for the development of ultra-thin body transistors. However, the polarity control of 2D transistors and the achievement of complementary logic functions remain critical challenges. Here, we report a doping-free strategy to modulate the polarity of WSe2 transistors using same contact metal but different integration methods. By applying low-energy van der Waals integration of Au electrodes, we observed robust and optimized p-type transistor behavior, which is in great contrast to the transistors fabricated on the same WSe2 flake using conventional deposited Au contacts with pronounced n-type characteristics. With the ability to switch majority carrier type and to achieve optimized contact for both electrons and holes, a doping-free logic inverter is demonstrated with higher voltage gain of 340, at the bias voltage of 5.5 V. Furthermore, the simple polarity control strategy is extended for realizing more complex logic functions such as NAND and NOR

Analysis of a Patch Model for the Dynamical Transmission of Echinococcosis

A patch model for echinococcosis due to dogs migration is proposed to explore the effect of dogs migration among patches on the spread of echinococcosis. We firstly define the basic reproduction number R0. The mathematical results show that the dynamics of the model can be completely determined by R0. If R01, the model is permanence and endemic equilibrium is globally asymptotically stable. According to the simulations, it is shown that the larger diffusion of dogs from the lower epidemic areas to the higher prevalence areas can intensify the spread of echinococcosis. However, the larger diffusion of dogs from the higher prevalence areas to the lower epidemic areas can reduce the spread and is beneficial for disease control

LncRNA-ATB inhibits the proliferation and invasion of NSCLC cells by regulating MiR-200s expression

Purpose: To investigate the effect of lncRNA-ATB on the proliferation and invasion of non-small cell lung cancer (NSCLC) cells, and its mechanism of action. Methods: LncRNA-ATB mRNA levels in carcinoma tissues and normal adjacent tissues of 38 NSCLC patients in Peking University Shougang Hospital were determined by reverse transcription-polymerase chain reaction (RT-PCR). Human NSCLC A549 cell line was divided into control and lncRNA-ATB inhibition (si-ATB) groups, respectively. The proliferation and invasion of cells in each group were assessed. Subsequently, the effect of lncRNA-ATB inhibition on the growth of NSCLC cells was evaluated by subcutaneous tumor formation assay. Results: The expression of lncRNA-ATB was significantly higher in carcinoma tissues than in normal adjacent tissues in NSCLC patients. Cell counting kit-8 (CCK-8) assay results showed that si-ATB group displayed a weakened ability of the cells to proliferate (p < 0.05). Furthermore, deoxyribonucleic acid (DNA) replication ability was weaker in si-ATB group than in the control group. Wound healing assay results showed that the migration ability of cells in the si-ATB group was lower than that in the control group. Also, lncRNA-ATB knockdown inhibited the invasion ability of human NSCLC cells (p < 0.05). Tumor formation assay data indicate that lncRNA-ATB knockdown significantly repressed the subcutaneous tumor formation ability of NSCLC cells. Furthermore, lncRNA-ATB knockdown in NSCLC cells up-regulated miR-200a, miR-200b and miR-200c. Conclusion: The expression level of LncRNA-ATB is elevated in carcinoma tissues of NSCLC patients, and its knockdown suppresses the proliferation and invasion of NSCLC cells by up-regulating miR-200s. This finding suggests that it is a potential strategy for the management of NSCLC patients