GNNFlow: A Distributed Framework for Continuous Temporal GNN Learning on Dynamic Graphs

Graph Neural Networks (GNNs) play a crucial role in various fields. However, most existing deep graph learning frameworks assume pre-stored static graphs and do not support training on graph streams. In contrast, many real-world graphs are dynamic and contain time domain information. We introduce GNNFlow, a distributed framework that enables efficient continuous temporal graph representation learning on dynamic graphs on multi-GPU machines. GNNFlow introduces an adaptive time-indexed block-based data structure that effectively balances memory usage with graph update and sampling operation efficiency. It features a hybrid GPU-CPU graph data placement for rapid GPU-based temporal neighborhood sampling and kernel optimizations for enhanced sampling processes. A dynamic GPU cache for node and edge features is developed to maximize cache hit rates through reuse and restoration strategies. GNNFlow supports distributed training across multiple machines with static scheduling to ensure load balance. We implement GNNFlow based on DGL and PyTorch. Our experimental results show that GNNFlow provides up to 21.1x faster continuous learning than existing systems

Study on stress simulation of concrete floor on transversely isotropic equivalent pile foundation during construction period

In the concrete pouring process of large pumping stations, the pile foundation plays an important role in supporting the upper structures, and also has a certain constraint on the concrete floor. In the numerical simulation calculation of construction period, to simplify the pre-processing, the volume ratio method is sometimes applied to regard the pile and surrounding soil foundation as the equivalent pile foundation, while the anisotropy of pile foundation is ignored, which will result in large calculation error of the horizontal stress of the concrete floor. Aiming at this problem, the anisotropy theory of materials is adopted in this paper to simulate the temperature field and stress field of the concrete floor both on non-equivalent pile foundation and equivalent pile foundation during construction period after compiling corresponding calculation program. The results show that when the ratio α of the horizontal elastic modulus to the vertical elastic modulus of equivalent pile foundation is about 1/20, the calculation result of the transversely isotropic equivalent pile foundation is approximately equal to the calculation result of the non-equivalent pile foundation (exact solution). It may provide some reference to similar engineering numerical simulation

A comparative study of prepulse inhibition in children with first episode schizophrenia and normal children

Objective·To explore the characteristics of sensory gating and its variation in children with first episode schizophrenia (COS) by using a new technique of prepulse suppression (PI).Methods·By using the ERP recording and analysis system of brain products, PI was detected in 56 patients with COS and 38 healthy children (NC) using the paradigm of single strong stimulus and weak stimulus+strong stimulus. The patients′ performance was comprehensively evaluated with Positive and Negative Syndrome Scale (PANSS), Social Disability Screening Schedule (SDSS), Social Adjustment Rating Scale (SSRS), and Family Interview Schedule (FIS).Results·The social objective support formed by summing up the above scales was compared with the quantitative stanard of social support [the standard of social support scale was (8±2) points, and the value of COS group was (10±3) points], and the difference was statistically significant (P=0.007). No correlation was found between PI and PANSS total score and each factor score (all P>0.05). The latency of startle reflex in the COS group was longer than that in the NC group [the NC group was (86±11) ms, the COS group was (97±13) ms, P=0.001]. In the COS group, the amplitude of startle reflex of weak stimulus+strong stimulus was higher, and the latency was longer than that of the NC group [NC group: (39±12) μV, COS group (47±21) μV, P=0.007; the latency of the normal group was (84±17) ms, and that of the COS group was (97±20) ms, P=0.003]. PI inhibition rate in the COS group was lower than that in the NC group [(66±32) % in the NC group, (43±37) % in the COS group, P=0.000].Conclusion·COS patients have the same PI abnormality as adult schizophrenia. The change of PI inhibition may be the result of biological markers reflecting the change of agitated emotion in COS patients

Estimation of HIV-1 incidence among five focal populations in Dehong, Yunnan: a hard hit area along a major drug trafficking route

<p>Abstract</p> <p>Background</p> <p>Since 1989 when the first 146 HIV positives in China were identified, Dehong Prefecture had been one of the areas hardest-hit by HIV in China. The local and national governments have put substantial financial resources into tackling the HIV epidemic in Dehong from 2004. The objective of this study was to track dynamic changes in HIV-1 prevalence and incidence among five focal populations in Dehong and to assess the impact of HIV prevention and control efforts.</p> <p>Methods</p> <p>Consecutive cross-sectional surveys conducted in five focal populations between 2004 and 2008. Specimens seropositive for HIV were tested with the BED IgG capture enzyme immunoassay to identify recent seroconversions (median, 155 days) using normalized optical density of 0.8 and adjustments.</p> <p>Results</p> <p>From 2004 to 2008, estimated annual HIV incidence among injecting drug users (IDUs) decreased significantly [from 15.0% (95% CI = 11.4%-18.5%) in 2004 to 4.3% (95% CI = 2.4%-6.2%) in 2008; trend test P < 0.0001]. The incidence among other focal populations, such as HIV discordant couples (varying from 5.5% to 4.7%), female sex workers (varying from 1.4% to 1.3%), pregnant women (0.1%), and pre-marital couples (0.2 to 0.1%) remained stable. Overall, the proportion of recent HIV-1 infections was higher among females than males (P < 0.0001).</p> <p>Conclusions</p> <p>The HIV epidemic in Dehong continued to expand during a five-year period but at a slowing rate among IDUs, and HIV incidence remains high among IDUs and discordant couples. Intensive prevention measures should target sub-groups at highest risk to further slow the epidemic and control the migration of HIV to other areas of China, and multivariate analysis is needed to explore which measures are more effective for different populations.</p

Risk Analysis of Vehicle Rear-End Collisions at Intersections

Aiming at solving a typical problem of past research using accident experience statistics of being unable to adapt to changing traffic flows, this paper provides an evaluation method of the risk of vehicle rear-end collisions at red-light-camera (RLC) intersections based on theoretical probabilities. Taking advantage of trajectory data of vehicles at the two similar intersections, which are Cao’an Road and Lvyuan Road with RLCs and Cao’an Road and Anhong Road without RLCs in Shanghai, a binary logit (BL) model of stop-and-go decision-making is established. Using the model and adjusting the headway and potential travel time, we can perform simulation and analysis of rear-end collisions. The result shows that this method is feasible to analyse the influence of RLCs on rear-end collisions. The analysis indicates that RLCs can cause higher speeds for vehicles passing the RLC intersection and more abnormal driving behaviors, which increase the difficulty of stop-and-go decision-making. RLCs do not always lead to an increase of rear-end collisions. For vehicles close to or far from intersection at the decision-making time, RLCs will significantly reduce the possibility of rear-end collisions; however, for vehicles in the potential travel time of 2 s∼3 s, RLCs will increase the probability of rear-end collisions

Improvement of particle swarm algorithm based on ultra-dense networking under 5G architecture

With the development of mobile communication technology, traditional intelligent terminal devices cannot meet the rapidly growing massive data computing requirements. Mobile edge computing provides low-latency and flexible computing solutions for mobile users in the Internet of Things. Considering the limited computing resources on the edge server and the dynamic needs of users in the network, this paper proposes to allocate the transmit power to optimize the transmission energy consumption through the binary particle swarm optimization algorithm. Analyzing request offloading and resource scheduling as a dual decision-making problem, a new multi-objective optimization algorithm based on particle swarm optimization algorithm is proposed to solve the problem. The simulation results show that the binary particle swarm optimization algorithm can save transmission energy and has good convergence. The proposed new algorithm outperforms existing algorithms in terms of response rate and can maintain good performance in dynamic edge computing networks

Risk Assessment in Urban Large-Scale Public Spaces Using Dempster-Shafer Theory: An Empirical Study in Ningbo, China

Urban Large-scale Public Spaces (ULPS) are important areas of urban culture and economic development, which are also places of the potential safety hazard. ULPS safety assessment has played a crucial role in the theory and practice of urban sustainable development. The primary objective of this study is to explore the interaction between ULPS safety risk and its influencing factors. In the first stage, an index sensitivity analysis method was applied to calculate and identify the safety risk assessment index system. Next, a Delphi method and information entropy method were also applied to collect and calculate the weight of risk assessment indicators. In the second stage, a Dempster-Shafer Theory (DST) method with evidence fusion technique was utilized to analyze the interaction between the ULPS safety risk level and the multiple-index variables, measured by four observed performance indicators, i.e., environmental factor, human factor, equipment factor, and management factor. Finally, an empirical study of DST approach for ULPS safety performance analysis was presented