Analysis of water vapour flux between alpine wetlands underlying surface and atmosphere in the source region of the Yellow River

An underlying wetland surface comprises soil, water and vegetation and is sensitive to local climate change. Analysis of the degree of coupling between wetlands and the atmosphere and a quantitative assessment of how environmental factors influence latent heat flux have considerable scientific significance. Using data from observational tests of the Maduo Observatory of Climate and Environment of the Northwest Institute of Eco-Environment and Resource, CAS, from June 1 to August 31, 2014, this study analysed the time-varying characteristics and causes of the degree of coupling(Ω factor)between alpine wetlands underlying surface and the atmosphere and quantitatively calculated the influences of different environmental factors(solar radiation and vapour pressure deficit) on latent heat flux. The results were as follows:(1) Due to diurnal variations of solar radiation and wind speed, a trend developed where diurnal variations of the Ω factor were small in the morning and large in the evening. Due to the vegetation growing cycle, seasonal variations of the Ω factor present a reverse "U" trend. These trends are similar to the diurnal and seasonal variations of the absolute control exercised by solar radiation over latent heat flux. This conforms to the Omega Theory.(2) The values for average absolute atmospheric factor(surface factor or total) control exercised by solar radiation and water vapour pressure are 0.20(0.02 or 0.22) and 0.005(-0.07 or-0.06) W/(m2·Pa), respectively. Generally speaking, solar radiation and water vapour pressure deficit exert opposite forces on latent heat flux.(3) At the underlying alpine wetland surface, solar radiation primarily influences latent heat flux through its direct effects(atmospheric factor controls). Water vapour pressure deficit primarily influences latent heat flux through its indirect effects(surface factor controls) on changing the surface resistance.(4) The average Ω factor in the underlying alpine wetland surface is high during the vegetation growing season, with a value of 0.38, and the degree of coupling between alpine wetland surface and atmosphere system is low. The actual measurements agree with the Omega Theory. The latent heat flux is mainly influenced by solar radiation.

Soil hydraulic conductivity and its influence on soil moisture simulations in the source region of the Yellow River——take Maqu as an example

Saturated hydraulic conductivity and unsaturated hydraulic conductivity which are influenced by soil are two important factors that affect soil water transport.In this paper,data supplied by the Chinese Academy of Sciences are used to determine true unsaturated hydrology values.Furthermore,in combination with observed,model simulation and experimental data,an improved saturated hydraulic conductivity parameterization scheme is carried out in CLM4.5 at a single point in the summer.The main results show that:(1)After improving saturated hydraulic conductivity in CLM4.5 through a parameterization modification,it is found that shallow layer soil moisture increases compared to the initial value;and(2)The numerical values of unsaturated hydraulic conductivities in the model are obviously larger than experimental values.By substituting the BrooksCorey soil water characteristic curve into the Mualem model,the value of unsaturated hydraulic conductivity is modified;(3)By using the modified value,it is found that the attenuating magnitude of simulated soil moisture caused by each rainfall event is reduced.The soil moisture variation in shallow layers(5,10 and 20 cm)could be better displayed.

Variation characteristics and prediction of pollutant concentration during winter in Lanzhou New District, China

PM2.5 and PM10 were the main air pollutants during winter in Lanzhou New District,China.In this paper,WRF model output combined with hourly monitoring data of pollutant concentration was used to analyze characteristics of the concentration change and to study the relationship between meteorological elements and PM10/PM2.5 in Lanzhou New District in January,2018.Meanwhile,the concentration changes of PM2.5 and PM10 were predicted by wavelet analysis combined with BP neural network.The results show that:(1)Due to the cold front process in winter,PM2.5 was negatively correlated with the water vapor mixing rate.PM10 was positively correlated with air temperature and negatively correlated with air pressure.(2)There was an inversion layer in the atmosphere near the high value day of PM2.5 and PM10,the surface was controlled by low pressure,low wind speed,and the situation of low value day of PM2.5 was the opposite.On the day of high value of PM10,the air temperature below 600 hPa was higher,and the wind speed near the surface was also higher.(3)Wavelet analysis combined with BP(Back Propagation)neural network had a good prediction effect on PM2.5,which could basically reflect the hourly change of PM2.5 concentration.However,the simulation effect of PM10 was poor,and the input parameters of surrounding pollutants should be added to improve the prediction effect.

Endovascular stent-induced alterations in host artery mechanical environments and their roles in stent restenosis and late thrombosis

Cardiovascular stent restenosis remains a major challenge in interventional treatment of cardiovascular occlusive disease.Although the changes in arterial mechanical environment due to stent implantation are the main causes of the initiation of restenosis and thrombosis,the mechanisms that cause this initiation are still not fully understood.In this article,we reviewed the studies on the issue of stent-induced alterations in arterial mechanical environment and discussed their roles in stent restenosis and late thrombosis from three aspects:(i)the interaction of the stent with host blood vessel,involve the response of vascular wall,the mechanism of mechanical signal transmission,the process of re-endothelialization and late thrombosis;(ii)the changes of hemodynamics in the lumen of the vascular segment and(iii)the changes of mechanical microenvironment within the vascular segment wall due to stent implantation.This review has summarized and analyzed current work in order to better solve the two main problems after stent implantation,namely in stent restenosis and late thrombosis,meanwhile propose the deficiencies of current work for future reference.

The Ecdysone and Notch Pathways Synergistically Regulate Cut at the Dorsal-Ventral Boundary in Drosophila Wing Discs

Metazoan development requires coordination of signaling pathways to regulate patterns of gene expression.In Drosophila,the wing imaginal disc provides an excellent model for the study of how signaling pathways interact to regulate pattern formation.The determination of the dorsal-ventral（DV） boundary of the wing disc depends on the Notch pathway,which is activated along the DV boundary and induces the expression of the homeobox transcription factor,Cut.Here,we show that Broad（Br）,a zinc-finger transcription factor,is also involved in regulating Cut expression in the DV boundary region.However,Br expression is not regulated by Notch signaling in wing discs,while ecdysone signaling is the upstream signal that induces Br for Cut upregulation.Also,we find that the ecdysone-Br cascade upregulates cut-lacZ expression,a reporter containing a 2.7 kb cut enhancer region,implying that ecdysone signaling,similar to Notch,regulates cut at the transcriptional level.Collectively,our findings reveal that the Notch and ecdysone signaling pathways synergistically regulate Cut expression for proper DV boundary formation in the wing disc.Additionally,we show br promotes Delta,a Notch ligand,near the DV boundary to suppress aberrant high Notch activity,indicating further interaction between the two pathways for DV patterning of the wing disc.

Germline silencing of UASt depends on the piRNA pathway

The success of the fruit fly Drosophila melanogaster as a model organism is heavily attributed to the expansive range and multitude of genetic and molecular tools available to modify gene expression at will. The GaI4/UAS binary system is one of the most important and widely used genetic tools in Drosophila designed for targeted gene expression （Brand and Perrimon, 1993）, which allows ectopic expression of any gene （or transgene） in specific tissues, independent of their native regulators. However, a drawback of the original UASt-transgene is its silence in germline cells--when the UASt-RFPhis transgene was driven by a ubiquitously expressed 6al4 under the ActinSC promoter （act-Gal4）, RFP expression was only detected in the somatic follicle cells, but not in the germline nurse cells or the oocyte （Fig. 1A）.