Assessment of activity and mechanism of action of β-Dglucan against dengue virus

Purpose: To assess the antiviral efficiency of β-D-glucan (BDG) on human liver cell line (WRL68) infected with dengue virus (DENV).Methods: Cytotoxic activity was assessed via 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. Solid-phase virus binding assay was used to determine the presence of a chemical affinity between dengue virus type 2 (DENV-2) and BDG. Plaque formation assay was performed to measure the suppression of DENV-2.Results: Plaque formation assay results revealed that the inhibition of DENV infection by BDG was effective at 400 μg/mL which occurred by inhibiting virus replication. BDG inhibited DENV replication and produced minimal toxicity on WRL68 cells at 600 μg/mL in a concentration-dependent manner. Treatment of DENV-2 with the highest concentration of the BDG resulted in 60, 55, and 50 % viability at 24, 48, and 72 h, respectively. Plaque formation and binding efficiency data confirmed that BDG protected the WRL68 cells against DENV-2.Conclusion: The results indicate that in infected cells, β-D-glucan was found to be potent in inhibiting replication of the dengue virus.Keywords: Dengue, β-D-glucan, Polysaccharide, Antiviral, Plaque formation, Binding efficienc

Learning Local Feature Descriptor with Motion Attribute for Vision-based Localization

In recent years, camera-based localization has been widely used for robotic applications, and most proposed algorithms rely on local features extracted from recorded images. For better performance, the features used for open-loop localization are required to be short-term globally static, and the ones used for re-localization or loop closure detection need to be long-term static. Therefore, the motion attribute of a local feature point could be exploited to improve localization performance, e.g., the feature points extracted from moving persons or vehicles can be excluded from these systems due to their unsteadiness. In this paper, we design a fully convolutional network (FCN), named MD-Net, to perform motion attribute estimation and feature description simultaneously. MD-Net has a shared backbone network to extract features from the input image and two network branches to complete each sub-task. With MD-Net, we can obtain the motion attribute while avoiding increasing much more computation. Experimental results demonstrate that the proposed method can learn distinct local feature descriptor along with motion attribute only using an FCN, by outperforming competing methods by a wide margin. We also show that the proposed algorithm can be integrated into a vision-based localization algorithm to improve estimation accuracy significantly.Comment: This paper will be presented on IROS1

Hydrological Response of Alpine Wetlands to ClimateWarming in the Eastern Tibetan Plateau

Alpine wetlands in the Tibetan Plateau (TP) play a crucial role in the regional hydrological cycle due to their strong influence on surface ecohydrological processes; therefore, understanding how TP wetlands respond to climate change is essential for projecting their future condition and potential vulnerability. We investigated the hydrological responses of a large TP wetland complex to recent climate change, by combining multiple satellite observations and in-situ hydro-meteorological records. We found different responses of runoff production to regional warming trends among three basins with similar climate, topography and vegetation cover but different wetland proportions. The basin with larger wetland proportion (40.1%) had a lower mean runoff coefficient (0.173 ± 0.006), and also showed increasingly lower runoff level (−3.9% year−1, p = 0.002) than the two adjacent basins. The satellite-based observations showed an increasing trend of annual non-frozen period, especially in the wetland-dominated region (2.64 day·year−1, p \u3c 0.10), and a strong extension of vegetation growing-season (0.26–0.41 day·year−1, p \u3c 0.10). Relatively strong increasing trends in evapotranspiration (ET) (~1.00 mm·year−1, p \u3c 0.01) and the vertical temperature gradient above ground surface (0.043 °C·year−1, p \u3c 0.05) in wetland-dominant areas were documented from satellite-based ET observations and weather station records. These results indicate recent surface drying and runoff reduction of alpine wetlands, and their potential vulnerability to degradation with continued climate warming

Climatic Controls on Spring Onset of the Tibetan Plateau Grasslands from 1982 to 2008

Understanding environmental controls on vegetation spring onset (SO) in the Tibetan Plateau (TP) is crucial to diagnosing regional ecosystem responses to climate change. We investigated environmental controls on the SO of the TP grasslands using satellite vegetation index (VI) from the 3rd Global Inventory Modeling and Mapping Studies (GIMMS3g) product, with in situ air temperature (Ta) and precipitation (Prcp) measurement records from 1982 to 2008. The SO was determined using a dynamic threshold method based on a 25% threshold of seasonal VI amplitude. We find that SO shows overall close associations with spring Ta, but is also subject to regulation from spring precipitation. In relatively dry but increasingly wetting (0.50 mm·year−1, p \u3c 0.10) grasslands (mean spring Prcp = 22.8 mm; Ta = −3.27 °C), more precipitation tends to advance SO (−0.146 day·mm−1, p = 0.150) before the mid-1990s, but delays SO (0.110 day·mm−1, p = 0.108) over the latter record attributed to lower solar radiation and cooler temperatures associated with Prcp increases in recent years. In contrast, in relatively humid TP grasslands (73.0 mm; −3.51 °C), more precipitation delays SO (0.036 day·mm−1, p = 0.165) despite regional warming (0.045 °C·year−1, p \u3c 0.05); the SO also shows a delaying response to a standardized drought index (mean R = 0.266), indicating a low energy constraint to vegetation onset. Our results highlight the importance of surface moisture status in regulating the phenological response of alpine grasslands to climate warming