Optimal L∞(L2)L^\infty(L^2) and L1(L2)L^1(L^2) a posteriori error estimates for the fully discrete approximations of time fractional parabolic differential equations

We derive optimal order a posteriori error estimates in the $L^\infty(L^2)$ and $L^1(L^2)$-norms for the fully discrete approximations of time fractional parabolic differential equations. For the discretization in time, we use the $L1$ methods, while for the spatial discretization, we use standard conforming finite element methods. The linear and quadratic space-time reconstructions are introduced, which are generalizations of the elliptic space reconstruction. Then the related a posteriori error estimates for the linear and quadratic space-time reconstructions play key roles in deriving global and pointwise final error estimates. Numerical experiments verify and complement our theoretical results.Comment: 22 page

Lajishankou Ophiolite Complex: Implications for Paleozoic Multiple Accretionary and Collisional Events in the South Qilian Belt

The Lajishan ophiolite complex in the Qilian Orogen is one of several ophiolites situated between the Qaidam and North China blocks that record episodic closure of the Proto-Tethyan Ocean. Detailed field relations and geochemical and geochronological studies are critical to unraveling the tectonic processes responsible for an extensive period of intraoceanic subduction that produced juvenile ophiolite/island arc terranes, which were obducted onto continental margins during ocean closure. The Lajishankou ophiolite complex crops out along the northern margin of the South Qilian belt and was thrust over a Neoproterozoic-Ordovician passive margin sequence that was deposited upon the Proterozoic Central Qilian block. The mafic rocks in Lajishankou ophiolite complex are the most abundant slices and can be categorized into three distinct groups based on petrological, geochemical, and geochronological characteristics: massive island arc tholeiites, 509-Ma back-arc dolerite dykes, and 491-Ma pillow basaltic and dolerite slices that are of seamount origin in a back-arc basin. These results, together with spatial relationships, indicate that the Cambrian island arc rocks, ophiolite complex, and accretionary complex developed between 530 and 480 Ma as a single, intraoceanic arc-basin system as a result of south directed subduction of the Proto-Tethyan Ocean prior to Early Ordovician obduction of this system onto the Central Qilian block. Final continental amalgamation involved continental collision of the Central Qilian block with the Qaidam block during the Late Ordovician. This model solves the long-lasting discussion on the emplacement of the Lajishan ophiolite and contributes to an improved understanding of multiple accretionary and collisional processes in the Qilian Orogen

The intestinal γδ T cells: functions in the gut and in the distant organs

Located in the frontline against the largest population of microbiota, the intestinal mucosa of mammals has evolved to become an effective immune system. γδ T cells, a unique T cell subpopulation, are rare in circulation blood and lymphoid tissues, but rich in the intestinal mucosa, particularly in the epithelium. Via rapid production of cytokines and growth factors, intestinal γδ T cells are key contributors to epithelial homeostasis and immune surveillance of infection. Intriguingly, recent studies have revealed that the intestinal γδ T cells may play novel exciting functions ranging from epithelial plasticity and remodeling in response to carbohydrate diets to the recovery of ischemic stroke. In this review article, we update regulatory molecules newly defined in lymphopoiesis of the intestinal γδ T cells and their novel functions locally in the intestinal mucosa, such as epithelial remodeling, and distantly in pathological setting, e.g., ischemic brain injury repair, psychosocial stress responses, and fracture repair. The challenges and potential revenues in intestinal γδ T cell studies are discussed

Rockburst mechanism caused by the mining-induced drainage of confined water in deep extra-thick aquifer

Extra-thick sandstone confined aquifer is widely spread in the overburden strata in Shaanxi and Inner Mongolia provinces. During coal mining, the water inflow in the working face is severe and the confined water level in the roof aquifer decreases significantly. The monitoring of rockbursts and high-energy seismicity shows that the mining-induced drainage of the confined water in the extra-thick sandstone confined aquifer has a certain effect on inducing rockburst. For a better understanding of rockburst mechanism as a result of the drainage of the roof confined water, the fluid-solid coupling numerical simulations were carried out. The mechanical behavior of rock mass with different pore water pressures and the evolution of stress-energy field in surrounding rock under the condition of mining-induced drainage of the confined water in the overburden aquifer were analyzed, and the effect of the mining-induced drainage of the confined water in aquifer on the stress field in surrounding rock was determined. On this basis, considering the effect of extra-thick strata on the dynamic and static stress in surrounding rock, the rockburst mechanism caused by the mining-induced drainage of the confined water in aquifer was proposed. The results show that the dynamic behaviors under extra-thick confined aquifer, including rockbursts and high energy seismicity, occur during the rapid drop of water level in overburden confined aquifer, and the mining-induced drainage of confined water causes stress disturbance to surrounding rock. Under the condition of mining-induced drainage of the confined water, the pore water pressure of the confined aquifer decreases, the strength and bearing capacity of the sandstone strata increase, and the overburden load is transferred to both sides of the goaf, which results in the increase of the stress and elastic energy in the surrounding rock. The effect of the mining-induced drainage of the confined water in aquifer on the stress-energy field is positively correlated with goaf scale and drainage degree, and negatively correlated with the distance between coal seam and confined aquifer, the thickness and strength of confined aquifer. The large-scale roof cantilever-hinged structures under the extra-thick confined aquifer lead to high static stress and strong dynamic stress in the surrounding rock. Under the effect of the mining-induced drainage of the confined water in the aquifer, the superimposed stress in coal and rock mass exceeds its critical load and the total energy released exceeds the energy consumed by its failure, which induces rockburst. In the process of rockburst, high static stress is the stress basis, and the stress disturbances caused by seismicity and the mining-induced drainage of the confined water are important inducements. In view of the influence of the mining-induced drainage of the confined water and the extra-thick strata structure on the rockburst risk, the confined water plugging of the extra-thick aquifer by ground grouting and optimizing the panel size were put forward. Field application indicates the two measures inferred above can reduce the effect of the mining-induced drainage of the confined water on the stress-energy field, and avoid the formation of the large-scale cantilever-hinged structures, which can reduce the rockburst risk significantly

Optimization of Micellar Electrokinetic Chromatography Method for the Simultaneous Determination of Seven Hydrophilic and Four Lipophilic Bioactive Components in Three Salvia Species

A micellar electrokinetic chromatography (MEKC) method was developed for the simultaneous determination of seven hydrophilic phenolic acids and four lipophilic tanshinones in three Salvia species. In normal MEKC mode using SDS as surfactant, the investigated 11 compounds could not be well separated. Therefore, several buffer modifiers including β-cyclodextrins (β-CD), ionic liquid 1-butyl-3-methylimidazolium tetrafluoroborate ([bmim]BF4) and organic solvents have been added to the buffer solution to improve the separation selectivity. Under the optimized conditions (BGE, 15 mM sodium tetraborate with 10 mM SDS, 5 mM β-CD, 10 mM [bmim]BF4 and 15% ACN (v/v) as additives; buffer pH, 9.8; voltage, 20 kV; temperature, 25 °C), the 11 investigated analytes could achieve baseline separation in 34 min. The proposed MEKC was additionally validated by evaluating the linearity (R2 ≥ 0.9965), LODs (0.27–1.39 μg·mL–1), and recovery (94.26%–105.17%), demonstrating this method was reproducible, accurate and reliable. Moreover, the contents of the 11 compounds in three Salvia species, including S. miltiorrhiza, S. przewalskii and S. castanea were analyzed. The result showed that the established MEKC method was simple and practical for the simultaneous determination of the hydrophilic and lipophilic bioactive components in Salvia species, which could be used to effectively evaluate the quality of these valued medicinal plants

On the Delay Performance Analysis in A Large-Scale Wireless Sensor Network

Abstract—We present a comprehensive delay performance measurement and analysis in an operational large-scale urban wireless sensor network. We build a light-weight delay measurement system in such a network and present a robust method to calculate per-packet delay. Through analysis of delay and system metrics, we seek to answer the following fundamental questions: what are the spatial and temporal characteristics of delay performance in a real network? what are the most important impacting factors and is there any practical model to capture those factors? what are the implications to protocol design? In this paper, we explore the important factors from the data in presence of various metrics and randomness, and show that the important factors are not necessarily the same with that in Internet. Further, we propose a delay model to capture those factors and validate it in the network. We revisit several prevalent protocol designs such as Collection Tree Protocol, opportunistic routing and Dynamic Switching based Forwarding, and show the implications to protocol designs. I