Optimized Angles of the Swing Hyperspectral Imaging Tower for Single Corn Plant

During recent years, hyperspectral imaging systems have been widely applied in the greenhouses for plant phenotyping purposes. Current imaging systems are mostly designed as either top view or side view imaging mode. Top-view is an ideal imaging angle for top leaves which are often more flat with more uniform reflectance. However, most bottom leaves are either blocked or shaded from top view. From side view, most leaves are viewable, and the entire structure can be imaged. However, at this angle most of the leaves are not facing the camera, which will impact the measurement quality. At the same time, there could be advantages with certain tilted imaging angle between top view and side view. Therefore, it’s important to explore the impact of different imaging angles to the phenotyping quality. For this purpose, we designed a swing hyperspectral imaging tower which enables us to rotate the camera and lighting source to capture images at any angle from side view (0◦) to top view (90◦). 36 corn plants were grown and divided into 3 different treatments: high nitrogen (N) and well-watered (control group), high N and drought-stressed, and low N and well-watered. Each plant was imaged at 7 different angles from 0◦ to 90◦ with an interval of 15◦. According to different treatments applied on experimental samples, two comparative pairs were set up: drought-stressed group vs. control group (Pair 1); N-deficiency group vs. control group (Pair 2). In this study, normalized difference vegetation index (NDVI) and relative water content (RWC) were computed and compared to determine optimized imaging angle(s). For NDVI, the imaging angle near to top view is optimized to separate Pair 1, while, the imaging angle near to side view is optimized to distinguish Pair 2. For RWC, partial least square regression (PLSR) models were applied to predict pixel-level RWC distribution of each plant, and higher imaging angles (close to top view) are better to tell the RWC distribution difference in Pair 1. In conclusion, higher imaging angles (close to top view) are better to separate different water treatments, while, lower imaging angles (close to side view) are better to separate different N treatments

Oil price shocks and their short- and long-term effects on the Chinese economy

A considerable body of economic literature shows the adverse economic impacts of oil-price shocks for the developed economies. However, there has been a lack of empirical study of this kind on China and other developing countries. This paper attempts to fill this gap by answering how and to what extent oil-price shocks impact China’s economy, emphasizing on the price transmission mechanisms. To that end, we develop a structural vector auto-regressive model. Our results show that an oil-price increase negatively affects output and investment, but positively affects inflation rate and interest rate. However, with the differentiated price control policies for materials and intermediates on the one hand and final products on the other hand in China, the impact on real economy, represented by real output and real investment, lasts much longer than that to price/monetary variables. Our decomposition results also show that the short-term impact, namely output decrease induced by the cut of capacity-utilization rate, is greater in the first one to two years, but the portion of the long-term impact, defined as the impact realized through an investment change, increases steadily and exceeds that of short-term impact at the end of the second year. Afterwards, the long-term impact dominates, and maintains for quite some time.Structural vector auto-regressive model; Unit root test; Error-correction model; Oil-price shocks; Price transmission mechanisms; Investment; Output; Producer/consumer price index; Census X-12 approach; China

Lithium Isotope Geochemistry of Marine Sediments.

While the isotope geochemistry of lithium in the marine environment is increasingly known, there are still outstanding problems concerning its oceanic budget and mantle-crust recycling that remain to be resolved. To evaluate the role of marine sediments in the oceanic budget, laboratory experiments were conducted to determine the extent of lithium adsorption on marine sediments and the magnitude of isotopic fractionation. Sediments from the Greenland margin were studied to gain further understanding of the sediment-water interaction. The isotopic compositions of the major types of marine sediments were characterized to understand the sedimentary cycle of lithium. The enhanced database permits a re-evaluation of the oceanic lithium budget. In the adsorption experiments, greater magnitude of adsorption was observed in river water than seawater demonstrating the effect of competition of major ions for sorption sites. The isotopic fractionation factors for adsorption on kaolinite, vermiculite, and Mississippi River suspended sediment are similar within uncertainty, giving a mean value of 1.024 +/- 0.003. In the comprehensive study of the sediments from the Greenland margin, the similarity between solid and pore water concentration profiles suggests that the sediments largely control the distribution of lithium in pore water. The isotopic compositions of the sediments are well correlated with source material as defined by lithology and bulk chemistry. Based on the isotopic data of various types of marine sediments, it is concluded that lithium isotopic compositions of marine sediments are dominated by terrigenous components and reflect local source. Most pelagic and hemipelagic sediments studied have isotopic compositions that are distinct from the mantle, making lithium isotopic ratio a valuable tracer for the subducted component in arc magmas. Among the sedimentary sinks evaluated in this study, namely incorporation in marine carbonates and biogenic silica, diffusion into sediments, and adsorption on marine sediments, only adsorption appears to be a significant sink for lithium in the oceans. The importance of the oceanic crust alteration at low and moderate temperatures as a lithium sink may be underestimated. Further insight into the lithium balance in the oceans depends on the characterization of water flux on the ocean ridge flank

Inflationary Effect of Oil-Price Shocks in an Imperfect Market: A Partial Transmission Input-output Analysis

This paper aims to examine the impacts of oil-price shocks on China’s price levels. To that end, we develop a partial transmission input-output model that captures the uniqueness of the Chinese market. We hypothesize and simulate price control, market factors and technology substitution - the three main factors that restrict the functioning of a price pass-through mechanism during oil-price shocks. Using the models of both China and the U.S., we separate the impact of price control from those of other factors leading to China’s price stickiness under oil-price shocks. The results show a sharp contrast between China and the U.S., with price control in China significantly preventing oil-price shocks from spreading into its domestic inflation, especially in the short term. However, in order to strengthen the economy’s resilience to oil-price shocks, the paper suggests a gradual relaxing of price control in China.Oil-price Shocks, Price Transmission, Price Control, Input-output Analysis, Inflation, Industrial Structure, China, the United States

Attention Trade-off between Two Types of User Contributions: Effects of Pinterest-Style Infinite Scroll Layouts on Creating Original Sharing and Appreciating Others’ Sharing

User contributions are critical to social commerce sites. Prior studies mainly examined motivational factors influencing user contributions. In the current study, we examine effects of interface layouts on user contributions, from the perspective of attention allocation. We also distinguish between the two types of user contributions: creating original sharing and appreciating others’ sharing. Since attention is a limited resource, we argue that interface layouts may lead to attention trade-off between the two types of user contributions. Leveraging an opportunity of a popular social commerce site’s transformation to Pinterest-style infinite scrolling layouts, we collected panel data. Empirical findings show that the new layouts design has opposite effects on the two types of user contribution: a positive effect on users’ appreciation of others’ sharing, but a negative effect on users’ original sharing. Some user characteristics moderate the effects. The findings yield important implications for research and websites design practice