Effects of soil flooding on photosynthesis and growth of Zea mays L. seedlings under different light intensities

Soil flooding is one of the major abiotic stresses that repress maize (Zea mays L.) growth and yield, and other environmental factors often influence soil flooding stress. This paper reports an experimental test of the hypothesis that light intensity can influence the responses of maize seedlings to soil flooding. In this experiment, maize seedlings were subjected to soil flooding at the two-leaf stage under control light (600 μmol m-2 s-1) or low light (150 μmol m-2 s-1) conditions. Under control light growth conditions, the average photosynthetic rate (PN), transpiration rate (E) and water use efficiency (WUE) were 70, 26 and 59%, respectively, higher in non-flooded than in flooded seedlings; and the average chlorophyll a (Chl a), chlorophyll b (Chl b) and Chl a+b were 31, 42 and 34%, respectively, higher in non-flooded than in flooded seedlings; and the average belowground biomass and total biomass were 52 and 34%, respectively, higher in non-flooded than in flooded seedlings. There was a slight decrease of seedling biomass in six days flooded seedlings under low light growth conditions. The effects of flooding on photosynthetic, seedling growth and shoot/root ratio were more pronounced under control light growth conditions than under low light growth conditions, which indicate that even for maize which is a C4 plant, relatively high light intensity still aggravated soil flooding stress, while low light growth condition mitigated soil flooding stress, and suggests that light effects should be considered when we study maize responses to soil flooding.Keywords: Biomass accumulation, gas exchange, light limitation, maize, stres

Partial discharge investigation under low air pressure and variable frequency for more-electric aircraft

More-electric-aircrafts (MEAs) are heading towards larger power, higher voltage, and more optimum architectures, it is extremely important to understand partial discharge (PD) behaviors under the challenging aeronautical power systems. PD under the pressure of 1-101 kPa and frequency of 50-1000 Hz is studied to emulate the practical situation with the consideration of insulation defects from electric machine windings. The high frequency current transformer (HFCT) is specifically employed to pick up partial discharge signals. Experimental results indicate that PD inception voltage (PDIV) decreases almost linearly with air pressure. As to the discharge amplitude, it increases first and then decreases as air pressure dropping. The highest discharge repetition rate and the number of discharges appear at 30 kPa. High frequency doubles the number of discharges without affecting PD amplitude. Low air pressure causes the phase shift and phase width of the phase-resolved partial discharge (PRPD) to increase, and the trend also is accelerated by high frequency. This experimental approach is beneficial to provide prerequisite knowledge in characterizing PD and assessing its potential adverse impact on the aeronautical power system and consequently contribute to optimizing the insulation design for MEA

Effects of Deep Tillage and Straw Returning on Soil Microorganism and Enzyme Activities

Two field experiments were conducted for two years with the aim of studying the effects of deep tillage and straw returning on soil microorganism and enzyme activity in clay and loam soil. Three treatments, (1) conventional tillage (CT), shallow tillage and straw returning; (2) deep tillage (DT), deep tillage and straw returning; and (3) deep tillage with no straw returning (DNT), were carried out in clay and loam soil. The results showed that deep tillage and straw returning increased the abundance of soil microorganism and most enzyme activities. Deep tillage was more effective for increasing enzyme activities in clay, while straw returning was more effective in loam. Soil microorganism abundance and most enzyme activities decreased with the increase of soil depth. Deep tillage mainly affected soil enzyme activities in loam at the soil depth of 20–30 cm and in clay at the depth of 0–40 cm. Straw returning mainly affected soil microorganism and enzyme activities at the depths of 0–30 cm and 0–40 cm, respectively

QTL Analysis of Shading Sensitive Related Traits in Maize under Two Shading Treatments

During maize development and reproduction, shading stress is an important abiotic factor influencing grain yield. To elucidate the genetic basis of shading stress in maize, an F2:3 population derived from two inbred lines, Zhong72 and 502, was used to evaluate the performance of six traits under shading treatment and full-light treatment at two locations. The results showed that shading treatment significantly decreased plant height and ear height, reduced stem diameter, delayed day-to-tassel (DTT) and day-to-silk (DTS), and increased anthesis-silking interval (ASI). Forty-three different QTLs were identified for the six measured traits under shading and full light treatment at two locations, including seven QTL for plant height, nine QTL for ear height, six QTL for stem diameter, seven QTL for day-to-tassel, six QTL for day-to-silk, and eight QTL for ASI. Interestingly, three QTLs, qPH4, qEH4a, and qDTT1b were detected under full sunlight and shading treatment at two locations simultaneously, these QTL could be used for selecting elite hybrids with high tolerance to shading and high plant density. And the two QTL, qPH10 and qDTS1a, were only detected under shading treatment at two locations, should be quit for selecting insensitive inbred line in maize breeding procedure by using MAS method

WhatTheySaid: enriching UK Parliament debates with Semantic Web

To improve the transparency of politics, the UK Parliament Debate archives have been published online for a long time. However there is still a lack of efficient way to deeply analysis the debate data. WhatTheySaid is an initiative to solve this problem by applying natural language processing and semantic Web technologies to enrich UK Parliament Debate archives and publish them as linked data. It also provides various data visualisations for users to compare debates over years

Optimal Reinsurance Strategy for an Insurer and a Reinsurer with Generalized Variance Premium Principle

This paper focuses on the optimal reinsurance problem with consideration of joint interests of an insurer and a reinsurer. In our model, the risk process is assumed to follow a Brownian motion with drift. The insurer can transfer the risk to the reinsurer via proportional reinsurance, and the reinsurance premium is calculated according to the variance and standard deviation premium principles. The objective is to maximize the expected exponential utility of the weighted sum of the insurer’s and the reinsurer’s terminal wealth, where the weight can be viewed as a regularization parameter to measure the importance of each party. By applying stochastic control theory, we establish the Hamilton–Jacobi–Bellman equation and obtain explicit expressions of optimal reinsurance strategies and optimal value functions. Furthermore, we provide some numerical simulations to illustrate the effects of model parameters on the optimal reinsurance strategies

The Effect of Firm-Specific Environmental Punishment on Stock Price Crash Risk: Evidence From China

Even though previous studies have investigated the effect of environmental regulation policy on stock price crash risk, little is known about how the firm-specific environmental punishment would impact stock price crash risks. By applying difference-in-difference method with manually collected firm-specific environmental punishment data for the listed firms in China, our study finds that the implemented environmental punishment leads to larger stock price crash risk accumulation of the punished firms. This effect can be mitigated by better information disclosure behavior, higher media reputation, healthy fundamentals, and optimal capital structure. Our study also finds the consecutive punishment effect only exists in a long period. Our work is among the first to rigorously analyze the effect of firm-specific environmental punishment on firm’s stock price crash risk. This research provides relevant policy suggestions on the environmental punishment practice

Effect of the Coordinative Optimization of Interruptible Loads in Primary Frequency Regulation on Frequency Recovery

When faults and disturbances occur in power systems, backup power resources respond to maintain the system’s frequency, and the frequency recovery effect is related to the primary frequency regulation of the reserve capacity provided by and the response speeds of the system’s generating units and interruptible loads. The relationships between a system’s frequency and the frequency regulation capacity of the generating units and the interruptible loads are different. In this paper, an index for the frequency recovery effect is proposed based on the static frequency adjustment coefficient of the interruptible load and the adjustment coefficients of the generating units, and an optimization model of an interruptible load participating in primary frequency regulation is built with the objective of minimizing the cost of the primary frequency regulation reserve that uses the system’s frequency recovery effect as a constraint. The simulation results verify the validity of the model

Spatial distributions, source apportionment and ecological risk of SVOCs in water and sediment from Xijiang River, Pearl River Delta

Xijiang River is an important drinking water source in Guangxi Province, China. Along the Xijiang River and surrounding tributary, the pollution profile of three important groups of semi-volatile organic compounds, including polycyclic aromatic hydrocarbons (PAHs), organochlorine pesticides (OCPs) and phthalate esters (PAEs), was analyzed. Relatively low levels of PAHs (64-3.7 x 10(2) ng L-1) and OCPs (16-70 ng L-1), but high levels of PAEs (7.9 x 10(2)-6.8 x 10(3) ng L-1) occurred in the water. Comparatively, low levels of OCPs (39-1.8 x 10(2) ng g(-1)) and PAEs (21-81 ng g(-1)), but high levels of PAHs (41-1.1 x 10(3) ng g(-1)) were found in sediment. Principal component analyses for source identification indicated petroleum-derived residues or coal and biomass combustion, and vehicular emission was the main sources for PAHs. The OCPs sources of each category were almost independent, whereas the new input of HCHs and p,p'-DDTs probably existed in some areas. PAEs were mainly originated from personal care products of urban sewage, plastic and other industrial sources. Ecological risk through the risk quotient analysis indicated a small or significant potential adverse effect on fish, daphnia and green algae. Nevertheless, the integrated risk of all pollutants should be taken into account in future study