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

Simple approach to estimating the van der Waals interaction between carbon nanotubes

The van der Waals (vdW) interactions between carbon nanotubes (CNTs) were studied based on the continuum Lennard-Jones model. It was found that all the vdW potentials between two arbitrary CNTs fall on the same curve when plotted in terms of certain reduced parameters, the well depth, and the equilibrium vdW gap. Based on this observation, an approximate approach is developed to obtain the vdW potential between two CNTs without time-consuming computations. The vdW potential estimated by this approach is close to that obtained from complex integrations. Therefore, the developed approach can greatly simplify the calculation of vdW interactions between CNTs

Probing the phonon surface interaction by wave packet simulation: effect of roughness and morphology

One way to reduce the lattice thermal conductivity of solids is to induce additional phonon surface scattering through nanostructures. However, how phonons interact with boundaries, especially at the atomic level, is not well understood. In this work, we performed two-dimensional atomistic wave packet simulations to investigate the phonon surface interaction. Emphasis has been given to the angular-resolved phonon reflection at smooth, periodically rough, and amorphous surfaces. We found that the acoustic phonon reflection at a smooth surface is not simply specular. Mode conversion can occur after reflection, and the detailed energy distribution after reflection will dependent on surface condition and polarization of incident phonon. At periodically rough surfaces, the reflected wave packet distribution does not follow the well-known Ziman's model, but shows a nonmonotonic dependence on the depth of surface roughness. When an amorphous layer is attached to the surface, the incident wave packet will be absorbed by the amorphous region, and results in quite diffusive reflection. Our results clearly show that the commonly used specular-diffusive model is not enough to describe the phonon reflection at a periodically rough surface, while an amorphous layer can induce strong diffusive reflection. This work provides a careful analysis of phonon reflection at a surface with different morphology, which is important to a better understanding of thermal transport in various nanostructures.Comment: 15pages, 9 figure

Activation of mammalian target of rapamycin mediates rat pain-related responses induced by BmK I, a sodium channel-specific modulator

The mammalian target of rapamycin (mTOR) is known to regulate cell proliferation and growth by controlling protein translation. Recently, it has been shown that mTOR signaling pathway is involved in long-term synaptic plasticity. However, the role of mTOR under different pain conditions is less clear. In this study, the spatiotemporal activation of mTOR that contributes to pain-related behaviors was investigated using a novel animal inflammatory pain model induced by BmK I, a sodium channel-specific modulator purified from scorpion venom. In this study, intraplantar injections of BmK I were found to induce the activation of mTOR, p70 ribosomal S6 protein kinase (p70 S6K) and eukaryotic initiation factor 4E-binding protein 1 (4E-BP1) in rat L5-L6 spinal neurons. In the spinal cord, mTOR, p70 S6K and 4E-BP1 were observed to be activated in the ipsilateral and contralateral regions, peaking at 1-2 h and recovery at 24 h post-intraplantar (i.pl.) BmK I administration. In addition, intrathecal (i.t.) injection of rapamycin - a specific inhibitor of mTOR - was observed to result in the reduction of spontaneous pain responses and the attenuation of unilateral thermal and bilateral mechanical hypersensitivity elicited by BmK I. Thus, these results indicate that the mTOR signaling pathway is mobilized in the induction and maintenance of pain-activated hypersensitivity

Single deep ultraviolet light emission from boron nitride nanotube film

Light in deep ultraviolet DUV region has a wide range of applications and the demand for finding DUV light emitting materials at nanoscale is increasingly urgent as they are vital for building miniaturized optic and optoelectronic devices. We discover that boron nitride nanotubes BNNTs with a well-crystallized cylindrical multiwall structure and diameters smaller than 10 nm can have single DUV emission at 225 nm 5.51 eV. The measured BNNTs are grown on substrate in the form of a thin film. This study suggests that BNNTs may work as nanosized DUV light sources for various applications. © 20

Building Cooperation in VoIP Network through a Reward Mechanism

In this paper, for solving the moral hazard problem of super nodes in VOIP network and achieving better communication quality, we establish a reward mechanism based on classical efficiency-wage models. In the reward mechanism, the function of reward is to encourage super nodes to contribute their bandwidth and cover their effort costs, whereas the function of fine is to prevent opportunistic super nodes from shirking. We consider that network quality and idle bandwidth are the essential criterions for selecting qualified super nodes. Once all super nodes can satisfy specific conditions, the required reward can be derived so as to improve the VoIP platform\u27s revenue. Moreover, we also suggest several targets both in technical and economic view that the platform provider can strive in order to boost his/her market share. In addition, the case of Skype is discussed in this study and we also examine its current pricing strategy

Comparison between Bubble CPAP and Ventilator-derived CPAP in Rabbits

BackgroundContinuous positive airway pressure (CPAP) is used in infants with respiratory distress and apnea. Bubble CPAP (B-CPAP) and ventilator-derived CPAP (V-CPAP) are two of the most popular CPAP modes, and use different pressure sources. However, few studies have been performed to compare their differences and effectiveness. This study was to determine whether B-CPAP and V-CPAP would have different effects on vital signs and arterial blood gas analysis.MethodsWe performed a randomized crossover study to measure vital signs, including mean blood pressure (MBP), heart rate (HR), and respiratory rate (RR), in 12 ketamine-anesthetized healthy rabbits receiving endotracheal intubation by tracheostomy with B-CPAP or V-CPAP. Arterial blood was also sampled and analyzed for PaO2, PaCO2, HCO3− and pH.ResultsWe observed statistically significant decreases in RR, pH and PaO2 with corresponding incrases in PaCO2 and HCO3− during the V-CPAP; however, no significant changes from baseline were observed for B-CPAP. Neither modality resulted in statistically significant changes in MBP or HR. Both forms of CPAP altered vital signs and arterial blood gases in a similar manner. There was a trend towards a lower percentage of change from baseline in all variables in B-CPAP compared with V-CPAP.ConclusionsOur results suggest that B-CPAP seems to be superior to V-CPAP in terms of its effect on arterial blood gases and vital signs. We speculate that B-CPAP could have certain protective effects that better preserve both arterial blood gases and vital signs when compared to V-CPAP. However, the results of this study still need to be tested by clinical study