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Flow velocity is fundamental in calculating related parameters of physical soil erosion models. It has been well known that rill flow velocity varies with developing rill form, which complicates and impedes the development of soil erosion models. In filed, rainfall erosion frequently occurs with pre-existing rills not damaged by tillage practices. However, the rill flow velocity in this case has received little attention. In this study, we investigated rill flow velocity regimes for both developing and stationary rills using 5 m-length plots in the laboratory. The experiments included two consecutive rainfalls, which had similar runoff rate. The first rainfall had an intensity of 90 mm h −1 , which generated well-developed rills; the second had an intensity of 60 mm h −1 and did not damage the rills formed by the first rainfall. The results show that, for a developing rill, rill flow velocity is higher in the lower slope than that in the upper slope, and rill flow velocity in the lower slope fluctuates much more over time as a result of the variation of rill morphology following rill development. With rill development, the rill flow velocity of the lower slope decreased responding to the stabilizing rill channel and exhibited a similar trend to that in upper slope. For a stationary rill, the rill flow velocities at both sections varied little over time, demonstrating that rill flow velocity is primarily influenced by rill morphology. Hence, the results suggested that the strength of fluctuation in rill flow velocity could be used to characterize the instantaneous intensity of soil erosion and active level of rill development. The channel of the stationary rill simply acted as transport pathways of sediment supplied by inter-rill erosion. The physical models of soil erosion should take into account the micro-topography on land surface related to the antecedently formed rills. [ABSTRACT FROM AUTHOR]

• Rill morphological parameters were changed with slope gradients. • Rill morphological parameters showed general increasing trend when slope position moved downward. • Most rill morphological parameters showed significant correlations with rill erosion amount. • Best morphological indicators are recommended for empirical rill erosion estimation. In the present study, the rill morphological parameters and their spatial distributions were investigated using indoor rainfall simulation experiments in combination with 3D terrestrial laser scanning technique. Moreover, the optimal rill morphological indicators for rill erosion evaluation were selected based on the relationship of rill morphological parameters and erosion amount. The results showed that total rill length (L), rill density (ρ), maximum width (W max), the degree of contour line departure (μ) and shape ratio (η) increased with the increase of slope gradient, whilst the mean rill depth (D mean), mean rill width (W mean) and width/depth ratio (W/D) decreased with the increase of slope gradient. The spatial distribution pattern of each rill morphology parameter was also changed with slope gradient, showing differences in upper slope, central slope and lower slope. Most of rill morphological parameters were highly correlated with rill erosion amount, except the mean rill width (W mean), degree of contour line departure (μ), and rill density (ρ). The plane area of rill (P area) or the degree of rill dissection (δ) was selected as the optimal morphological parameter to predict rill erosion amount, followed by the maximum area of cross section (CS max), the maximum rill depth (D max), and the mean rill depth (D mean). In particular, the parameters of CS max and D max are recommended for rill erosion estimation based on the convenience and ease of data acquisition. [ABSTRACT FROM AUTHOR]

According to the Institute of International Education, China has become a major receiving country of international students, like the United States, United Kingdom, Australia, and Canada. The rapid development of international education in China evidences a major progress in the infrastructure of Chinese higher education. While internationalization creates unprecedented opportunities for the knowledge economy in China, it simultaneously poses unparalleled challenges for Chinese higher education (An & Chiang, 2015) and one of these challenges is the medium of instruction (MOI). While English has been widely taught in China since 1978 (McArthur, 2005), it was not until the turn of the century that English was endorsed as the medium of instruction for the so-called Chinese-English bilingual education. [ABSTRACT FROM AUTHOR]

The efficacy of an inactivated foot-and-mouth disease (FMD) vaccine is mainly dependent on the integrity of the foot-and-mouth disease virus (FMDV) particles. At present, the standard method to quantify the active component, the 146S antigen, of FMD vaccines is sucrose density gradient (SDG) analysis. However, this method is highly operator dependent and difficult to automate. In contrast, the enzyme-linked immunosorbent assay (ELISA) is a time-saving technique that provides greater simplicity and sensitivity. To establish a valid method to detect and quantify the 146S antigen of a serotype O FMD vaccine, a double-antibody sandwich (DAS) ELISA was compared with an SDG analysis. The DAS ELISA was highly correlated with the SDG method (R2 = 0.9215, P<0.01). In contrast to the SDG method, the DAS ELISA was rapid, robust, repeatable and highly sensitive, with a minimum quantification limit of 0.06 μg/mL. This method can be used to determine the effective antigen yields in inactivated vaccines and thus represents an alternative for assessing the potency of FMD vaccines in vitro. But it still needs to be prospectively validated by analyzing a new vaccine preparation and determining the proper protective dose followed by an in vivo vaccination-challenge study to confirm the ELISA findings. [ABSTRACT FROM AUTHOR]