Estimation of potential wildfire behavior characteristics to assess wildfire danger in southwest China using deep learning schemes.

Accurate estimation of potential wildfire behavior characteristics (PWBC) can improve wildfire danger assessment. However, wildfire behavior has been estimated by most fire spread models with immeasurable uncertainties and difficulties in large-scale applications. In this study, a PWBC estimation model (named PWBC-QR-BiLSTM) was proposed by coupling the Bi-directional Long Short-Term Memory (BiLSTM) and quantile regression (QR) methods. Multi-source data, including fuel, weather, topography, infrastructure, and landscape variables, were input into the PWBC-QR-BiLSTM model to estimate the potential rate of spread (ROS) and fire radiative power (FRP) over western Sichuan of China, and then to estimate the probability density of ROS and FRP. Daily ROS and FRP were extracted from the Global Fire Atlas and the MOD14A1/MYD14A1 product. The optimal PWBC-QR-BiLSTM model was determined using the Non-dominated Sorting Genetic Algorithm Ⅱ (NAGA-Ⅱ). Results showed that the PWBC-QR-BiLSTM performed well in estimating potential ROS and FRP with high accuracy (ROS: R2 > 0.7 and MAPE<30%, FRP: R2 > 0.8 and MAPE<25%). The modal PWBC values extracted from the estimated probability density were closer to the observed values, which can be regarded as a good indicator for wildfire danger assessment. The variable importance analysis also verified that fuel and infrastructure variables played an important role in driving wildfire behavior. This study suggests the potential of utilizing artificial intelligence to estimate PWBC and its probability density to improve the guidance on wildfire management.

Effect of needle diameter, type and volume of contrast agent on intervertebral disc degeneration in rats with discography.

PURPOSE: Discography can increase disc degeneration, but the influence of different discography variables on the degeneration of discs has not been reported. The aim of this study was to investigate the effects of discography variables of needle diameter, type of contrast agent and volume of contrast agent on disc degeneration. METHODS: Three separate experiments examined needle diameter, and type and volume of contrast agent. Coccygeal discs (Co7-10) adult male rats were used. X-rays were used to detect the disc height degeneration index at 1, 2 and 4 weeks after the procedure. MRI was used to study the changes in the disc structure and the signal intensity of IVD 2 and 4 weeks after the procedure. Disc water content and histology were measured at 4 weeks after the procedure. RESULTS: A 21-g needle significantly increased disc degeneration when compared with the 30-g needle as detected by X-ray, MRI, disc water content and histology (P < 0.05). Two microlitres of iodine significantly decreased the disc MRI signal and water content at 4 weeks compared with the same volume of normal saline (P < 0.05). Three microlitres of iodine significantly increased disc degeneration when compared with 2 µl iodine, as detected by X-ray, MRI, disc water content and histology at 4 weeks (P < 0.05). CONCLUSION: To reduce disc degeneration after discography, it may be best to choose a smaller needle size, minimize the use of contrast agent and use non-ionic contrast agents with osmotic pressure similar to the intervertebral disc. These slides can be retrieved under Electronic Supplementary Material.

Se@SiO2 nanocomposites suppress microglia-mediated reactive oxygen species during spinal cord injury in rats.

Selenium (Se) is an essential trace element with strong antioxidant activity, showing a great prospect in the treatment of spinal cord injury (SCI). However, the narrow gap between the beneficial and toxic effects has limited its further clinical application. In this experiment, we used porous Se@SiO2 nanocomposites (Se@SiO2) modified by nanotechnology as a new means of release control to investigate the anti-oxidative effect in SCI. In vitro Se@SiO2 toxicity, anti-oxidative and anti-inflammatory effects on microglia were assayed. In vivo we investigated the protective effect of Se@SiO2 to SCI rats. Neurological function was evaluated by Basso, Beattie and Bresnahan (BBB). The histopathological analysis, microglia activation, oxidative stress, inflammatory factors (TNF-α, IL-1ß and IL-6) and apoptosis were detected at 3 and 14 days after SCI. The favorable biocompatibility of Se@SiO2 suppressed microglia activation, which is known to be associated with oxidative stress and inflammation in vivo and in vitro. In addition, Se@SiO2 improved the rat neurological function and reduced apoptosis via caspase-3, Bax and Bcl-2 pathways in SCI. Se@SiO2 was able to treat SCI and reduce oxidative stress, inflammation and apoptosis induced by microglia activation, which may provide a novel and safe strategy for clinical application.