Res2Net: A New Multi-scale Backbone Architecture

Representing features at multiple scales is of great importance for numerous vision tasks. Recent advances in backbone convolutional neural networks (CNNs) continually demonstrate stronger multi-scale representation ability, leading to consistent performance gains on a wide range of applications. However, most existing methods represent the multi-scale features in a layer-wise manner. In this paper, we propose a novel building block for CNNs, namely Res2Net, by constructing hierarchical residual-like connections within one single residual block. The Res2Net represents multi-scale features at a granular level and increases the range of receptive fields for each network layer. The proposed Res2Net block can be plugged into the state-of-the-art backbone CNN models, e.g., ResNet, ResNeXt, and DLA. We evaluate the Res2Net block on all these models and demonstrate consistent performance gains over baseline models on widely-used datasets, e.g., CIFAR-100 and ImageNet. Further ablation studies and experimental results on representative computer vision tasks, i.e., object detection, class activation mapping, and salient object detection, further verify the superiority of the Res2Net over the state-of-the-art baseline methods. The source code and trained models are available on https://mmcheng.net/res2net/.Comment: 11 pages, 7 figure

2-(Hydrazonomethyl)phenol

The conformation of the title compound, C7H8N2O, is stabilized by an intra­molecular O—H⋯N hydrogen bond. The crystal structure shows inter­molecular N—H⋯O hydrogen bonds

A New Business Model of Electronic Commerce with Innovative Strategies

There are a lot of problems that make the business of electronic stores very difficult, especially for those firms that lack the required expertise and resources for running an electronic business. This study proposes a new business model of electronic commerce (EC), which aims to tackle those problems and help enterprises run electronic stores well. This model applies the franchise system of chain store, a very successful modern business model, to the management of electronic stores to take advantage of the chain’s competitive power by integrating individual affiliate sites as a whole. There are eight components in the model. Implementation strategies of the model, which are quite different from those generic strategies commonly used in implementing business models, are also proposed. The feasibility of the model and its implementation strategies were validated using the Nominal Group Technique (NGT), the case study, and the questionnaire survey approaches. Finally, practical implications for applying the model are discussed, and directions for further study are also suggested

Diffusion Model-Augmented Behavioral Cloning

Imitation learning addresses the challenge of learning by observing an expert's demonstrations without access to reward signals from environments. Most existing imitation learning methods that do not require interacting with environments either model the expert distribution as the conditional probability p(a|s) (e.g., behavioral cloning, BC) or the joint probability p(s, a) (e.g., implicit behavioral cloning). Despite its simplicity, modeling the conditional probability with BC usually struggles with generalization. While modeling the joint probability can lead to improved generalization performance, the inference procedure can be time-consuming and it often suffers from manifold overfitting. This work proposes an imitation learning framework that benefits from modeling both the conditional and joint probability of the expert distribution. Our proposed diffusion model-augmented behavioral cloning (DBC) employs a diffusion model trained to model expert behaviors and learns a policy to optimize both the BC loss (conditional) and our proposed diffusion model loss (joint). DBC outperforms baselines in various continuous control tasks in navigation, robot arm manipulation, dexterous manipulation, and locomotion. We design additional experiments to verify the limitations of modeling either the conditional probability or the joint probability of the expert distribution as well as compare different generative models

2,2′-(p-Phenyl­ene)bis­(4,5-dihydro-1H-imidazol-3-ium) bis­(3-nitro­benzoate)

In the title compound, C12H16N4 +·2C7H4NO4 −, the complete 2,2′-(p-phenyl­ene)bis­(4,5-dihydro-1H-imidazol-3-ium) (bib) dication is generated by crystallographic inversion symmetry. The bib cations reside on crystallographic inversion centers, which coincide with the centroids of the respective benzene rings. In the cation, the imidazole ring adopts an envelop conformation with the flap atom displaced by 0.082 (3) Å from the plane through the other ring atoms. In the crystal, the cations and anions are linked through inter­molecular N—H⋯O hydrogen bonds, forming chains running along the a axis. C—H⋯O inter­actions also occur. Weak π–π contacts between the imidazole rings of bib and between the benzene rings of NB [centroid–centroid distances = 3.501 (1) and 3.281 (2) Å, respectively] may further stabilize the structure

The diagnostic role of resting myocardial blood flow in STEMI patients after revascularization

BackgroundThe value of semiquantitative resting myocardial perfusion imaging (MPI) in coronary artery disease (CAD) is limited. At present, quantitative MPI can be performed by a new cadmium zinc tellurium single-photon emission computed tomography (CZT-SPECT) scan. The quantitative index of resting myocardial blood flow (MBF) has received little attention, and its manifestations and clinical value in the presence of unstable coronary blood flow have not been clarified.PurposeIn patients with ST-segment elevation myocardial infarction (STEMI), whether resting MBF can provide additional value of blood flow than semi-quantitative resting MPI is not sure. We also explored the influencing factors of resting MBF.MethodsThis was a retrospective clinical study. We included 75 patients with STEMI in the subacute phase who underwent resting MPI and dynamic scans after reperfusion therapy. General patient information, STEMI-related data, MPI, gated MPI (G-MPI), and resting MBF data were collected and recorded. According to the clinically provided culprit vessels, the resting MBF was divided into ischemic MBF and non-ischemic MBF. The paired Wilcoxon signed-rank test was used for resting MBF. The receiver operating characteristic (ROC) curves were used to determine the optimal threshold for ischemia, and multiple linear regression analysis was used to analyze the influencing factors of resting MBF.ResultsThere was a statistically significant difference between the ischemic MBF and non-ischemic MBF [0.59 (0.47–0.72) vs. 0.76 (0.64–0.93), p < 0.0001]. The ROC curve analysis revealed that resting MBF could identify ischemia to a certain extent, with a cutoff value of 0.5975, area under the curve (AUC) = 0.666, sensitivity = 55.8%, and specificity = 68.7%. Male sex and summed rest score (SRS) were influencing factors for resting MBF.ConclusionTo a certain extent, resting MBF can suggest residual ischemia after reperfusion therapy in patients with STEMI. There was a negative correlation between male sex, SRS, and ischemic MBF. A lower resting MBF may be associated with more severe myocardial ischemia

2-[4-(4,5-Dihydro-1H-imidazol-2-yl)phen­yl]-4,5-dihydro-1H-imidazol-3-ium 4-amino­benzoate

In the cation of the title compound, C12H15N4 +·C7H6NO2 −, the benzene ring makes dihedral angles of 30.51 (9) and 25.64 (9)° with the imidazole and imidazolinium rings, respectively. In the crystal, inter­molecular N—H⋯O and N—H⋯N hydrogen-bonding inter­actions link the mol­ecules into a three-dimensional network