Hybrid Graph: A Unified Graph Representation with Datasets and Benchmarks for Complex Graphs

Graphs are widely used to encapsulate a variety of data formats, but real-world networks often involve complex node relations beyond only being pairwise. While hypergraphs and hierarchical graphs have been developed and employed to account for the complex node relations, they cannot fully represent these complexities in practice. Additionally, though many Graph Neural Networks (GNNs) have been proposed for representation learning on higher-order graphs, they are usually only evaluated on simple graph datasets. Therefore, there is a need for a unified modelling of higher-order graphs, and a collection of comprehensive datasets with an accessible evaluation framework to fully understand the performance of these algorithms on complex graphs. In this paper, we introduce the concept of hybrid graphs, a unified definition for higher-order graphs, and present the Hybrid Graph Benchmark (HGB). HGB contains 23 real-world hybrid graph datasets across various domains such as biology, social media, and e-commerce. Furthermore, we provide an extensible evaluation framework and a supporting codebase to facilitate the training and evaluation of GNNs on HGB. Our empirical study of existing GNNs on HGB reveals various research opportunities and gaps, including (1) evaluating the actual performance improvement of hypergraph GNNs over simple graph GNNs; (2) comparing the impact of different sampling strategies on hybrid graph learning methods; and (3) exploring ways to integrate simple graph and hypergraph information. We make our source code and full datasets publicly available at https://zehui127.github.io/hybrid-graph-benchmark/.Comment: Preprint. Under review. 16 pages, 5 figures, 11 table

Forward and Backward Information Retention for Accurate Binary Neural Networks

Weight and activation binarization is an effective approach to deep neural network compression and can accelerate the inference by leveraging bitwise operations. Although many binarization methods have improved the accuracy of the model by minimizing the quantization error in forward propagation, there remains a noticeable performance gap between the binarized model and the full-precision one. Our empirical study indicates that the quantization brings information loss in both forward and backward propagation, which is the bottleneck of training accurate binary neural networks. To address these issues, we propose an Information Retention Network (IR-Net) to retain the information that consists in the forward activations and backward gradients. IR-Net mainly relies on two technical contributions: (1) Libra Parameter Binarization (Libra-PB): simultaneously minimizing both quantization error and information loss of parameters by balanced and standardized weights in forward propagation; (2) Error Decay Estimator (EDE): minimizing the information loss of gradients by gradually approximating the sign function in backward propagation, jointly considering the updating ability and accurate gradients. We are the first to investigate both forward and backward processes of binary networks from the unified information perspective, which provides new insight into the mechanism of network binarization. Comprehensive experiments with various network structures on CIFAR-10 and ImageNet datasets manifest that the proposed IR-Net can consistently outperform state-of-the-art quantization methods

Haem oxygenase delays programmed cell death in wheat aleurone layers by modulation of hydrogen peroxide metabolism

Haem oxygenase-1 (HO-1) confers protection against a variety of oxidant-induced cell and tissue injury in animals and plants. In this report, it is confirmed that programmed cell death (PCD) in wheat aleurone layers is stimulated by GA and prevented by ABA. Meanwhile, HO activity and HO-1 protein expression exhibited lower levels in GA-treated layers, whereas the hydrogen peroxide (H2O2) content was apparently increased. The pharmacology approach illustrated that scavenging or accumulating H2O2 either delayed or accelerated GA-induced PCD. Furthermore, pretreatment with the HO-1 specific inhibitor, zinc protoporphyrin IX (ZnPPIX), before exposure to GA, not only decreased HO activity but also accelerated GA-induced PCD significantly. The application of the HO-1 inducer, haematin, and the enzymatic reaction product of HO, carbon monoxide (CO) aqueous solution, both of which brought about a noticeable induction of HO expression, substantially prevented GA-induced PCD. These effects were reversed when ZnPPIX was added, suggesting that HO in vivo played a role in delaying PCD. Meanwhile, catalase (CAT) and ascorbate peroxidase (APX) activities or transcripts were enhanced by haematin, CO, or bilirubin (BR), the catalytic by-product of HO. This enhancement resulted in a decrease in H2O2 production and a delay in PCD. In addition, the antioxidants butylated hydroxytoluene (BHT), dithiothreitol (DTT), and ascorbic acid (AsA) were able not only to delay PCD but also to mimic the effects of haematin and CO on HO up-regulation. Overall, the above results suggested that up-regulation of HO expression delays PCD through the down-regulation of H2O2 production

An Easy Method for Pressure Measurement in Microchannels Using Trapped Air Compression in a One-End-Sealed Capillary

Pressure is one basic parameter involved in microfluidic systems. In this study, we developed an easy capillary-based method for measuring fluid pressure at one or multiple locations in a microchannel. The principal component is a commonly used capillary (inner diameter of 400 μm and 95 mm in length), with one end sealed and calibrated scales on it. By reading the height (h) of an air-liquid interface, the pressure can be measured directly from a table, which is calculated using the ideal gas law. Many factors that affect the relationship between the trapped air volume and applied pressure (papplied) have been investigated in detail, including the surface tension, liquid gravity, air solubility in water, temperature variation, and capillary diameters. Based on the evaluation of the experimental and simulation results of the pressure, combined with theoretical analysis, a resolution of about 1 kPa within a full-scale range of 101.6–178 kPa was obtained. A pressure drop (Δp) as low as 0.25 kPa was obtained in an operating range from 0.5 kPa to 12 kPa. Compared with other novel, microstructure-based methods, this method does not require microfabrication and additional equipment. Finally, we use this method to reasonably analyze the nonlinearity of the flow-pressure drop relationship caused by channel deformation. In the future, this one-end-sealed capillary could be used for pressure measurement as easily as a clinical thermometer in various microfluidic applications

Study on Desiccation Tolerance and Biochemical Changes of <i>Sassafras tzumu</i> (Hemsl.) Hemsl. Seeds

The deciduous tree species Sassafras tzumu (Hemsl.) Hemsl., unique to China, holds significant economic and ecological value. However, its seeds exhibit poor storage tolerance and rapid decline in seed vigor. This study primarily investigates the desiccation tolerance of S. tzumu seeds. The results show that S. tzumu seeds have recalcitrant seed characteristics, with a semi-inactivation water content (at which point half of the seeds lose viability) of 20.7%. As desiccation progresses, seed viability decreases significantly; at a reduced water content of 11.93%, only 18.3% of the seeds remain viable, while most lose their viability completely. Relative electrolytic leakage (REC) and H2O2 content gradually increase during this process, while MDA content initially decreases before increasing again, exhibiting distinct trends compared to antioxidant enzyme activities such as superoxide dismutase (SOD), peroxidase (POD), and catalase (CAT). SOD and POD activities exhibit an initial increase followed by a rapid decrease, whereas CAT activity shows a decline followed by a rapid increase. Dehydration to 15% water content in seeds is a key turning point in the process of seed desiccation in S. tzumu, and CAT is an enzyme key to maintaining seed viability. Both the accumulation of toxins and the decline in the activity of the antioxidant system contribute to the susceptibility of S. tzumu seeds to drought stress, a characteristic common to all recalcitrant seeds. To maintain high seed viability above 70% during storage, it is crucial to ensure water content above 23.58%