The Outcome of the 2022 Landslide4Sense Competition: Advanced Landslide Detection from Multi-Source Satellite Imagery

The scientific outcomes of the 2022 Landslide4Sense (L4S) competition organized by the Institute of Advanced Research in Artificial Intelligence (IARAI) are presented here. The objective of the competition is to automatically detect landslides based on large-scale multiple sources of satellite imagery collected globally. The 2022 L4S aims to foster interdisciplinary research on recent developments in deep learning (DL) models for the semantic segmentation task using satellite imagery. In the past few years, DL-based models have achieved performance that meets expectations on image interpretation, due to the development of convolutional neural networks (CNNs). The main objective of this article is to present the details and the best-performing algorithms featured in this competition. The winning solutions are elaborated with state-of-the-art models like the Swin Transformer, SegFormer, and U-Net. Advanced machine learning techniques and strategies such as hard example mining, self-training, and mix-up data augmentation are also considered. Moreover, we describe the L4S benchmark data set in order to facilitate further comparisons, and report the results of the accuracy assessment online. The data is accessible on Future Development Leaderboard for future evaluation at https://www.iarai.ac.at/landslide4sense/challenge/ , and researchers are invited to submit more prediction results, evaluate the accuracy of their methods, compare them with those of other users, and, ideally, improve the landslide detection results reported in this article

Molecular Dynamics Investigation of the Influence of Voids on the Impact Mechanical Behavior of NiTi Shape-Memory Alloy

To date, research on the physical and mechanical behavior of nickel-titanium shape-memory alloy (NiTi SMA) has focused on the macroscopic physical properties, equation of state, strength constitution, phase transition induced by temperature and stress under static load, etc. The behavior of a NiTi SMA under high-strain-rate impact and the influence of voids have not been reported. In this present work, the behavior evolution of (100) single-crystal NiTi SMA and the influencing characteristics of voids under a shock wave of 1.2 km/s are studied by large-scale molecular dynamics calculation. The results show that only a small amount of B2 austenite is transformed into B19’ martensite when the NiTi sample does not pass through the void during impact compression, whereas when the shock wave passes through the hole, a large amount of martensite phase transformation and plastic deformation is induced around the hole; the existence of phase transformation and phase-transformation-induced plastic deformation greatly consumes the energy of the shock wave, thus making the width of the wave front in the subsequent propagation process wider and the peak of the foremost wave peak reduced. In addition, the existence of holes disrupts the orderly propagation of shock waves, changes the shock wave front from a plane to a concave surface, and reduces the propagation speed of shock waves. The calculation results show that the presence of pores in a porous NiTi SMA leads to significant martensitic phase transformation and plastic deformation induced by phase transformation, which has a significant buffering effect on shock waves. The results of this study provide great guidance for expanding the application of NiTi SMA in the field of shock

Finite Element Simulation of NiTiNb Shape Memory Alloy Pipe-Joint Subjected to Coupled Transformation and Plastic Deformation

The assembling process of Ni47Ti44Nb9 alloy pipe joints considering the phase transformation and plasticity was numerically simulated for the first time with a developed constitutive model. The simulated process was based on the experimental material parameters, which were determined with the experimental tensile results of Ni47Ti44Nb9 shape memory alloy (SMA) and steel bars. The results showed that, after assembly, the Mises stress distributed uniformly along the longitudinal direction of the NiTiNb joint, but nonuniformly along the radial direction. The maximum σeq does not appear at the inner wall of the joints due to the coupling effect of the plastic deformation and the recoverable transformation. The contact pressure distributed uniformly along the circumferential direction, but nonuniformly along the longitudinal direction. The sizes of the SMA joint and the pipe should be properly matched to ensure contact during the stage of the rapid reverse phase transformation to obtain stable connection performance. The pull-out force was also computed, and the results were in good agreement with the experimental results. The results obtained can provide available information for the optimization of the design parameters of the high-performance SMA pipe-joint, such as inner diameter and assembly clearance

The effect of lentivirus-mediated PSPN genetic engineering bone marrow mesenchymal stem cells on Parkinson's disease rat model.

Persephin (PSPN) is one of the neurotrophic factors of the glial cell line-derived neurotrophic factor (GDNF) family ligands (GFLs) which have been found to promote the survival of specific populations of neurons. The aim of this study was to assess the potential therapeutic function of gene-modified mesenchymal stem cells (MSCs)-Lv-PSPN-MSCs in 6-OHDA-induced Parkinson's disease (PD) rats models. Here, we worked on the isolation, purification, identification and amplification of MSCs in vitro. The expression analysis revealed that several of the neural marker proteins like nestin, GFAP and S100 were expressed by rat MSCs. MES23.5 cells co-cultured with Lv-PSPN-MSCs showed less 6-OHDA induced cell death than control cells in vitro. When Lv-PSPN-MSCs were injected into the striatum of PD rats, we observed the survival rate, migration, differentiation and the behavior change of PD rats. We found that Lv-PSPN-MSCs showed higher survival rate in rat brain compared with Lv-null-MSCs. Rotational behavior showed that rats receiving Lv-PSPN-MSCs showed the most significant improvement compared with those in other groups. HPLC results showed the content of DA in striatum of rats which received Lv-PSPN-MSCs was highest compared with those in other groups. In conclusion, our results suggest that transplantation of Lv-PSPN-MSCs can lead to remarkable therapeutic effects in PD rats

Expression of PSPN genes in transduced rMSCs detected by Western blots, RT-PCR and immunofluorescence.

<p>(<b>A</b>) RT-PCR detection of PSPN expression in rMSCs. (<b>B</b>) The relative density of bands was calculated using GAPDH as a loading control. (<b>C</b>) Western blots analysis of cell extracts from rMSCs after transduction with Lv-PSPN. Equal amounts of cell extracts were used in all lanes. β-actin was used as a loading control. (<b>D</b>) Western blotting films from three independent experiments were scanned and the relative density of protein bands was calculated using β-actin as a loading control. At least three independent experiments were performed. Data are presented as means±SD. Immunofluorescence staining for PSPN (E–H). (<b>E</b>) EGFP-labeled rMSCs. (<b>F</b>) Expression of PSPN genes in transduced rMSCs. (<b>G</b>) Hoechst33258-stained nuclei. (<b>H</b>) Merged images. Scale bar = 200 µm.</p

The change of EGFP-labeled rMSCs after stereotactic injection into the striatum of PD rats.

<p>(<b>A</b>) Cells were injected into the striatum through needle passage with microsyringe. (<b>B–E</b>) The fluorescence intensity in Lv-PSPN-MSCs group is stronger than Lv-null-MSCs group no matter in the first week or second week. Over a period of 4 weeks following grafting, EGFP-labeled rMSCs could be detected at various locations. rMSCs could be detected within the striatum (<b>F</b>) while others had already attached either to the contralateral striatum (<b>G</b>), periventricular regions (<b>H–I</b>) and cerebral cortex (<b>J</b>). Single cells even exhibit processes resembling neuronal morphologies (<b>K</b>). Scale bar = 200 µm.</p

Expression of PSPN genes in transduced rMSCs detected by Western blots, RT-PCR and immunofluorescence.

<p>(<b>A</b>) RT-PCR detection of PSPN expression in rMSCs. (<b>B</b>) The relative density of bands was calculated using GAPDH as a loading control. (<b>C</b>) Western blots analysis of cell extracts from rMSCs after transduction with Lv-PSPN. Equal amounts of cell extracts were used in all lanes. β-actin was used as a loading control. (<b>D</b>) Western blotting films from three independent experiments were scanned and the relative density of protein bands was calculated using β-actin as a loading control. At least three independent experiments were performed. Data are presented as means±SD. Immunofluorescence staining for PSPN (E–H). (<b>E</b>) EGFP-labeled rMSCs. (<b>F</b>) Expression of PSPN genes in transduced rMSCs. (<b>G</b>) Hoechst33258-stained nuclei. (<b>H</b>) Merged images. Scale bar = 200 µm.</p

Neural marker expression in rMSCs cultured inα-medium.

<p>(<b>A</b>) Expression of the astrocyte marker GFAP (red) in 80±2.6% of rMSCs, the cells rarely exhibit neuronal-like morphologies. (<b>B</b>) The neuronal stem cell marker Nestin staining (red) in 10.8±5.9%of the rMSCs. (<b>C</b>) Expression of the neuronal markerβ3-tubulin (red) in 89.2±4.5 of the total rMSCs population. (<b>D</b>) Almost 65±2.2% of the rMSCs is immunopositive for the neuronal progenitor marker NES (green). (<b>E</b>) About 77.2±4.2% of the rMSCs expresses the glial cell marker S100 (green). (<b>F</b>) Also the microglia maker IBA-1 (green) is expressed by a majority of cells. Blue: Hoechst 33258 counterstaining. Scale bar = 200 µm.</p

List of primary antibodies used in this study.

<p>List of primary antibodies used in this study.</p

Effects of grafting with engineered rMSCs on apomorphine-induced rotational behaviors.

<p>Average rotational turns per 30 min are shown at different time points (interval = 1 week, n = 10). Data are expressed as mean ± SD. Average rotational rates of the PD group and of vehicle group were not changed from baseline. In contrast, the average rotational rates of PD rats implanted with MSCs or Lv-null-MSCs significantly decreased (<i>P</i><0.05). The greatest decrease, however, was observed in PD rats implanted with Lv-PSPN-MSCs (<i>P</i><0.001). In addition, this group showed significantly greater behavioral improvement than that of MSCs group (<i>P</i><0.05) or Lv-null-MSCs group (<i>P</i><0.05).</p