In contrast with nature scenes, aerial scenes are often composed of many objects crowdedly distributed on the surface in bird's view, the description of which usually demands more discriminative ...features as well as local semantics. However, when applied to scene classification, most of the existing convolution neural networks (ConvNets) tend to depict global semantics of images, and the loss of low- and mid-level features can hardly be avoided, especially when the model goes deeper. To tackle these challenges, in this paper, we propose a multiple-instance densely-connected ConvNet (MIDC-Net) for aerial scene classification. It regards aerial scene classification as a multiple-instance learning problem so that local semantics can be further investigated. Our classification model consists of an instance-level classifier, a multiple instance pooling and followed by a bag-level classification layer. In the instance-level classifier, we propose a simplified dense connection structure to effectively preserve features from different levels. The extracted convolution features are further converted into instance feature vectors. Then, we propose a trainable attention-based multiple instance pooling. It highlights the local semantics relevant to the scene label and outputs the bag-level probability directly. Finally, with our bag-level classification layer, this multiple instance learning framework is under the direct supervision of bag labels. Experiments on three widely-utilized aerial scene benchmarks demonstrate that our proposed method outperforms many state-of-the-art methods by a large margin with much fewer parameters.
We generalized the recently introduced "radiation model", as an analog to the generalization of the classic "gravity model", to consolidate its nature of universality for modeling diverse mobility ...systems. By imposing the appropriate scaling exponent λ, normalization factor κ and system constraints including searching direction and trip OD constraint, the generalized radiation model accurately captures real human movements in various scenarios and spatial scales, including two different countries and four different cities. Our analytical results also indicated that the generalized radiation model outperformed alternative mobility models in various empirical analyses.
Anomalous taxi trajectories are those chosen by a small number of drivers that are different from the regular choices of other drivers. These anomalous driving trajectories provide us an opportunity ...to extract driver or passenger behaviors and monitor adverse urban traffic events. Because various trajectory clustering methods have previously proven to be an effective means to analyze similarities and anomalies within taxi GPS trajectory data, we focus on the problem of detecting anomalous taxi trajectories, and we develop our trajectory clustering method based on the edit distance and hierarchical clustering. To achieve this objective, first, we obtain all the taxi trajectories crossing the same source–destination pairs from taxi trajectories and take these trajectories as clustering objects. Second, an edit distance algorithm is modified to measure the similarity of the trajectories. Then, we distinguish regular trajectories and anomalous trajectories by applying adaptive hierarchical clustering based on an optimal number of clusters. Moreover, we further analyze these anomalous trajectories and discover four anomalous behavior patterns to speculate on the cause of an anomaly based on statistical indicators of time and length. The experimental results show that the proposed method can effectively detect anomalous trajectories and can be used to infer clearly fraudulent driving routes and the occurrence of adverse traffic events.
Most neutralizing antibodies against Middle East respiratory syndrome coronavirus (MERS-CoV) target the receptor-binding domain (RBD) of the spike glycoprotein and block its binding to the cellular ...receptor dipeptidyl peptidase 4 (DPP4). The epitopes and mechanisms of mAbs targeting non-RBD regions have not been well characterized yet. Here we report the monoclonal antibody 7D10 that binds to the N-terminal domain (NTD) of the spike glycoprotein and inhibits the cell entry of MERS-CoV with high potency. Structure determination and mutagenesis experiments reveal the epitope and critical residues on the NTD for 7D10 binding and neutralization. Further experiments indicate that the neutralization by 7D10 is not solely dependent on the inhibition of DPP4 binding, but also acts after viral cell attachment, inhibiting the pre-fusion to post-fusion conformational change of the spike. These properties give 7D10 a wide neutralization breadth and help explain its synergistic effects with several RBD-targeting antibodies.
Quick Access Recorders (QARs) provide an important data source for Flight Operation Quality Assurance (FOQA) and flight safety. It is generally characterized by large volume, high-dimensionality and ...high frequency, and these features result in extreme complexities and uncertainties in its usage and comprehension. In this study, we proposed a Time-Feature Attention (TFA)-based Convolutional Auto-Encoder (TFA-CAE) network model to extract essential flight features from QAR data. As a case study, we used the QAR data landing at the Kunming Changshui International Airport and Lhasa Gonggar International Airport as the experimental data. The results show that (1) the TFA-CAE model performs the best in extracting representative flight features in comparison to some traditional or similar approaches, such as Principal Component Analysis (PCA), Convolutional Auto-Encoder (CAE), Self-Attention-based CAE (SA-CAE), Gate Recurrent Unit based Auto-Encoder (GRU-AE) and TFA-GRU-AE models; (2) flight patterns corresponding to different runways can be recognized; and (3) anomalous flights can effectively deviate from many observations. Overall, the TFA-CAE model provides a well-established technique for further usage of QAR data, such as flight risk detection or FOQA.
Both the high temperature and particle environment at the downhole greatly aggravate the abrasive wear and shorten the service life of the fluororubber (FKM) seal seriously in drilling engineering. ...At present, there is less awareness of the tribological behavior of seals in such complex working conditions. In this work, the abrasive wear performance of the thermally degraded FKM seal was tested in the form of simulating the intrusion of abrasive particles into the interface. Results show that the wear of both rubber seals and metal counterparts is exacerbated. Through the analysis of the wear scar morphology and friction coefficient, it is revealed that more abrasive caves scatter on the surface due to the mechanical degradation of the FKM. These abrasion caves reduce the tendency of particles to escape from the caves and prolong the abrasive action. Furthermore, the abrasion cave alters the particle motion from sliding to rolling, which leads to more caves generated on the surface of the hard tribo-pair. These results enhance the understanding of the abrasive wear for FKM seals and hopefully contribute to the promotion of seals used in hot abrasive particle environments.
Ferroptosis is one of the critical pathological events in spinal cord injury. Erythropoietin has been reported to improve the recovery of spinal cord injury. However, whether ferroptosis is involved ...in the neuroprotective effects of erythropoietin on spinal cord injury has not been examined. In this study, we established rat models of spinal cord injury by modified Allen's method and intraperitoneally administered 1000 and 5000 IU/kg erythropoietin once a week for 2 successive weeks. Both low and high doses of erythropoietin promoted recovery of hindlimb function, and the high dose of erythropoietin led to better outcome. High dose of erythropoietin exhibited a stronger suppressive effect on ferroptosis relative to the low dose of erythropoietin. The effects of erythropoietin on inhibiting ferroptosis-related protein expression and restoring mitochondrial morphology were similar to those of Fer-1 (a ferroptosis suppressor), and the effects of erythropoietin were largely diminished by RSL3 (ferroptosis activator). In vitro experiments showed that erythropoietin inhibited RSL3-induced ferroptosis in PC12 cells and increased the expression of xCT and Gpx4. This suggests that xCT and Gpx4 are involved in the neuroprotective effects of erythropoietin on spinal cord injury. Our findings reveal the underlying anti-ferroptosis role of erythropoietin and provide a potential therapeutic strategy for treating spinal cord injury.
Abstract
Traditional lithium-ion batteries with graphite anodes have gradually been limited by the glass ceiling of energy density. As a result, lithium metal batteries (LMBs), regarded as the ideal ...alternative, have attracted considerable attention. However, lithium is highly reactive and susceptible to most electrolytes, resulting in poor cycle performance. In addition, lithium grows Li dendrites during charging, adversely affecting the safety of LMBs. Therefore, LMBs are more sensitive to the chemical composition of electrolytes and their relative ratios (concentrations). Recently, concentrated electrolytes have been widely demonstrated to be friendly to lithium metal anodes (LMAs). This review focuses on the progress of concentrated electrolytes in LMBs, including the solvation structure varying with concentration, unique functions in stabilizing the LMA, and their interfacial chemistry with LMA.
Dysfunction of vascular smooth muscle cells (VSMCs) plays a critical role in the pathogenesis of intracranial aneurysm (IA). Circular RNAs (circRNAs) have been implicated in the pathogenesis of IA by ...reducing microRNA (miRNA) activity. In this paper, we investigated the precise roles of circRNA ADP ribosylation factor interacting protein 2 (circ-ARFIP2, circ_0021001) in VSMC dysfunction. The levels of circ-ARFIP2, miR-338-3p and kinase insert domain receptor (KDR) were detected by quantitative real-time polymerase chain reaction (qRT-PCR) or western blot. Ribonuclease (RNase) R and subcellular fractionation assays were used to assess the stability and localization of circ-ARFIP2, respectively. Cell viability was detected by Cell Counting Kit-8 (CCK-8) assay, and cell invasion was measured by transwell assay. Cell proliferation was gauged by 5-Ethynyl-2’-Deoxyuridine (EdU) assay. Cell migration was evaluated by transwell and wound-healing assays. Targeted correlations among circ-ARFIP2, miR-338-3p and KDR were validated by dual-luciferase reporter and RNA immunoprecipitation (RIP) assays. Circ-ARFIP2 and KDR were underexpressed and miR-338-3p was overexpressed in the arterial wall tissues of IA patients. Overexpression of circ-ARFIP2 in human umbilical artery smooth muscle cells (HUASMCs) showed a significant promotion in cell proliferation, migration and invasion. Mechanistically, circ-ARFIP2 targeted miR-338-3p, and circ-ARFIP2 regulated cell behaviors by miR-338-3p. KDR was a direct and functional target of miR-338-3p. Moreover, KDR was a downstream effector of circ-ARFIP2 function. Circ-ARFIP2 regulated KDR expression by targeting miR-338-3p. Our present findings demonstrated that the increased level of circ-ARFIP2 enhanced HUASMC proliferation, migration and invasion at least in part by the miR-338-3p/KDR axis.
A mitochondria-targeted NIR probe based on the FRET mechanism was developed. It shows ultra-large Stokes shifts (460 nm) and emission shifts (285 nm). Furthermore, we also realized the imaging of SO2 ...in living SKOV-3 cells, zebrafish and living mice which may be useful for understanding the biological roles of SO2 in mitochondria and in vivo.
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