A Simulation Study on the Clouds Microphysical Processes of Heavy Precipitation in Hebei Area Caused by"Lekima"

During the period of the super typhoon"Lekima"(No.1909)landed on the coast of North China,a high-resolution numerical simulation study was carried out with the WRF model on the clouds microphysical process of heavy precipitation.The results showed that(1)the water vapor convergence tended to develop and strengthen on the way forward of typhoon center,and the evolution of water vapor convergence zone was closely related to the development of typhoon asymmetric structure,and had a good corresponding relationship with the falling zone of the rainstorm.(2)The eastern coast of Hebei was located in the big-value area of water vapor transport belt in the northwest quadrant of the typhoon.Below 850 hPa,northeast wind appeared,and warm humid water vapor was transported from marine area to terrestrial by typhoon.Affected by upper-level westerly trough,westerly wind was dominated above 700 hPa,and water vapor convergence was transported from low level to upper level,and several rainstorm center appeared.(3)In the spiral rain bands of typhoon,the big-value center of graupel particles cooperated with the warm cloud enriched with water content,and the ground would produce a center of heavy precipitation,and the precipitation center of pure warm cloud appeared in 117.5°E.This phenomenon rarely occurred during continental cloud precipitation.Therefore,the contribution of warm cloud precipitation mechanism to the typhoon spiral rain belt should be emphasized.

Study on Physical Characteristics of a Precipitation Cloud System in Hebei Province in Spring by Aircraft Observation

Using data of airborne particle measurement system, weather radar and Ka-band millimeter wave cloud-meter, physical structure characteristics of a typical stable stratiform cloud in Hebei Province on February 27, 2018 was analyzed. Research results showed that the detected cloud system was the precipitation stratiform cloud in the later stage of development. The cloud layer developed stably, and the vertical structure was unevenly distributed. The concentration of small cloud particles in high-level clouds was low, and it fluctuated greatly in space, and presented a discontinuous distribution state. The concentration of large cloud particles and precipitation particles was high, which was conducive to the growth of cloud droplets and the aggregation of ice crystals. The concentration of small cloud particles and the content of supercooled water were high in the middle and low-level clouds. The precipitation cloud system had a significant hierarchical structure, which conformed to the "catalysis-supply" mechanism. From the upper layer to the lower layer, the cloud particle spectrum was mainly in the form of single peak or double peak distribution, which showed a monotonic decreasing trend in general. The spectral distribution of small cloud particles in the cloud was discontinuous, and the high-value areas of spectral concentration of large cloud particles and precipitation particles were concentrated in the upper part of the cloud layer, and the particle spectrum was significantly widened. There was inversion zone at the bottom of the cloud layer, which was conducive to the continuous increase of particle concentration and the formation of large supercooled water droplets.

TMEM181:a key mediator of cytolethal distending toxin required for Wnt signaling activity

Wnt signaling pathway plays critical roles in a variety of embryonic developmental processes and also controls homeostatic selfrenewal in a number of adult tissues(Flaherty and Dawn,2008;Nusse and Clevers,2017).At the cell membrane,Wnt ligands bind to the seven transmembrane receptors of Frizzled family and the co-receptors to activate intracellular signaling pathway,including theβ-catenin-dependent canonical Wnt signaling pathway,the noncanonical planar cell polarity(PCP)pathway and the Wnt/calcium pathway(Flaherty and Dawn,2008).In mammals,WNT4,WNT5A.

Coordination of PSS and FACTS Damping Controllers to Improve Small Signal Stability of Large-scale Power Systems

This paper presents an approach for designing parameters of power system stabilizer(PSS)and FACTS damping controllers in a large scale practical power system.The objective is maximizing damping ratio of the target mode,and tracking technology(MTT)is used to avoid frequent alternations of target mode in optimization procedures.An improved planted growth simulation algorithm(IPGSA),which has high search efficiency and quick convergence speed,is proposed to optimize controller parameters coordinately.Based on case study of a large-scale power grid,and by using local and interregional low-frequency oscillation modes as target modes,simulation results verify proposed method in this paper.Furthermore,coordination optimization strategy adapted to multi-operating conditions demonstrates that the proposed approach is robust.

Molecular characterization of two suppressor of cytokine signaling 1 genes(SOCS1a and SOCS1b) in chickens

Suppressor of cytokine signaling 1(SOCS1)protein can inhibit the signal transduction triggered by some cytokines or hormones and thus are important in many physiological/pathological processes, including innate and adaptive immunity, inflammation, and development in mammals. However, there is sparse information about their structure, tissue expression, in birds, where their biological functions remain unknown. In this study,we cloned and characterized two SOCS1 genes(named c SOCS1 a and c SOCS1b) from chickens. SOCS1 a is predicted to encode a 207-amino acid protein, which shares high amino acid sequence identity(64%–67%) with human and mouse SOCS1. Besides SOCS1 a, a novel SOCS1 b gene was also identified in chickens and other non-mammalian vertebrates including Xenopus tropicalis.Chicken SOCS1 b is predicted to encode a 212-amino acid protein, which shares only 30%–32% amino acid sequence identity with human SOCS1 and c SOCS1 a. RT-PCR assay revealed that both c SOCS1 a and c SOCS1 b are widely expressed in all chicken tissues. Using a luciferase reporter assay system, we further demonstrated that transient expression of c SOCS1 a and c SOCS1 b can significantly inhibit chicken growth hormone(GH)- or prolactin(PRL)-induced luciferase activities of Hep G2 cells expressing c GH receptor(or c PRL receptor), indicating that SOCS1 a and SOCS1 b proteins can negatively regulate GH/PRL signaling. Taken together, these data suggest that both c SOCS1 a and c SOCS1 b may function as negative regulators of cytokine/hormone actions, such as modulation of GH/PRL actions in chickens.

流形上的k-Hessian方程的Neumann边值问题

本文考虑紧致具有全脐边界的Riemann流形上k-Hessian方程的Neumann边值问题;通过对k-Hessian方程的解做零阶、一阶、二阶估计和使用连续性方法,得到流形上k-Hessian方程的Neumann边值问题的存在性结果.