Memory Augmented Graph Neural Networks for Sequential Recommendation

The chronological order of user-item interactions can reveal time-evolving and sequential user behaviors in many recommender systems. The items that users will interact with may depend on the items accessed in the past. However, the substantial increase of users and items makes sequential recommender systems still face non-trivial challenges: (1) the hardness of modeling the short-term user interests; (2) the difficulty of capturing the long-term user interests; (3) the effective modeling of item co-occurrence patterns. To tackle these challenges, we propose a memory augmented graph neural network (MA-GNN) to capture both the long- and short-term user interests. Specifically, we apply a graph neural network to model the item contextual information within a short-term period and utilize a shared memory network to capture the long-range dependencies between items. In addition to the modeling of user interests, we employ a bilinear function to capture the co-occurrence patterns of related items. We extensively evaluate our model on five real-world datasets, comparing with several state-of-the-art methods and using a variety of performance metrics. The experimental results demonstrate the effectiveness of our model for the task of Top-K sequential recommendation.Comment: Accepted by the 34th AAAI Conference on Artificial Intelligence (AAAI 2020

Seasonal variation of the deep limb of the Pacific Meridional Overturning circulation at Yap-Mariana junction

© The Author(s), 2020. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Wang, J., Ma, Q., Wang, F., Lu, Y., & Pratt, L. J. Seasonal variation of the deep limb of the Pacific Meridional Overturning circulation at Yap-Mariana junction. Journal of Geophysical Research: Oceans, 125(7), (2020): e2019JC016017, doi:10.1029/2019JC016017.This study reveals the seasonal variability of the lower and upper deep branches of the Pacific Meridional Overturning Circulation (L‐PMOC and U‐PMOC) in the Yap‐Mariana Junction (YMJ) channel, a major gateway for deep flow into the western Pacific. On the western side of the YMJ channel, mooring observations in 2017 and in 1997 show the seasonal phase of the L‐PMOC at depths of 3,800–4,400 m: strong northward flow with speed exceeding 20 cm s−1 and lasting from December to next May and weak flow during the following 6 months. On the eastern side of the channel, mooring observations during 2014–2017 show two southward deep flows with broadly seasonal phases, one being the return flow of L‐PMOC below ~4,000 m and with the same phase of L‐PMOC but reduced magnitude. The second, shallower, southward deep flow corresponds to the U‐PMOC observed within 3,000–3,800 m and with opposite phase of L‐PMOC, that is, strong (weak) southward flow appearing during June–November (December–May). Seasonal variations of the L‐PMOC and U‐PMOC are accompanied by the seasonal intrusions of the Lower and Upper Circumpolar Waters (LCPW and UCPW) in lower and upper deep layers, which change the isopycnal structure and the deep currents in a way consistent with geostrophic balance.This study is supported by the National Natural Science Foundation of China (grants 91958204 and 41776022), the Strategic Priority Research Program of the Chinese Academy of Sciences (grant XDA22000000), the Key Research Program of Frontier Sciences, CAS (grant QYZDB‐SSW‐SYS034). F. Wang thanks the support from the Scientific and Technological Innovation Project by Qingdao National Laboratory for Marine Science and Technology (grant 2016ASKJ12), the National Program on Global Change and Air‐Sea Interaction (grant GASI‐IPOVAI‐01‐01), and the National Natural Science Foundation of China (grants 41730534 and 41421005). L. Pratt gratefully acknowledges the support by NSF (grant OCE‐1657870). Jianing Wang and Qiang Ma contributed equally to this work

Pathways, volume transport, and seasonal variability of the lower deep limb of the Pacific Meridional Overturning Circulation at the Yap-Mariana Junction

© The Author(s), 2021. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Wang, J., Wang, F., Lu, Y., Ma, Q., Pratt, L. J., & Zhang, Z. Pathways, volume transport, and seasonal variability of the lower deep limb of the Pacific Meridional Overturning Circulation at the Yap-Mariana Junction. Frontiers in Marine Science, 8, (2021): 672199, https://doi.org/10.3389/fmars.2021.672199.The lower deep branch of the Pacific Meridional Overturning Circulation (L-PMOC) is responsible for the deep-water transport from Antarctic to the North Pacific and is a key ingredient in the regulation of global climate through its influence on the storage and residence time of heat and carbon. At the Pacific Yap-Mariana Junction (YMJ), a major gateway for deep-water flowing into the Western Pacific Ocean, we deployed five moorings from 2018 to 2019 in the Eastern, Southern, and Northern Channels in order to explore the pathways and variability of L-PMOC. We have identified three main patterns for L-PMOC pathways. In Pattern 1, the L-PMOC intrudes into the YMJ from the East Mariana Basin (EMB) through the Eastern Channel and then flows northward into the West Mariana Basin (WMB) through the Northern Channel and southward into the West Caroline Basin (WCB) through the Southern Channel. In Pattern 2, the L-PMOC intrudes into the YMJ from both the WCB and the EMB and then flows into the WMB. In Pattern 3, the L-PMOC comes from the WCB and then flows into the EMB and WMB. The volume transports of L-PMOC through the Eastern, Southern, and Northern Channels all exhibit seasonality. During November–April (May–October), the flow pathway conforms to Pattern 1 (Patterns 2 and 3), and the mean and standard deviation of L-PMOC transports are −4.44 ± 1.26 (−0.30 ± 1.47), −0.96 ± 1.13 (1.75 ± 1.49), and 1.49 ± 1.31 (1.07 ± 1.10) Sv in the Eastern, Southern, and Northern Channels, respectively. Further analysis of numerical ocean modeling results demonstrates that L-PMOC transport at the YMJ is forced by a deep pressure gradient between two adjacent basins, which is mainly determined by the sea surface height (SSH) and water masses in the upper 2,000-m layer. The seasonal variability of L-PMOC transport is attributed to local Ekman pumping and westward-propagating Rossby waves. The L-PMOC transport greater than 3,500 m is closely linked to the wind forcing and the upper ocean processes.This study was supported by the Strategic Priority Research Program of the Chinese Academy of Sciences (grant XDA22000000), the National Natural Science Foundation of China (grants 91958204 and 41776022), the Key Research Program of Frontier Sciences, CAS (grant QYZDB-SSW-SYS034), and the International Partnership Program of CAS (grant 133137KYSB20180056). FW thanks the support from the National Natural Science Foundation of China (grants 41730534 and 41421005). QM thanks the support by the National Natural Science Foundation of China (grant 42006003)

Environmental efficiency of ports under the dual carbon goals: Taking China’s Bohai-rim ports as an example

In 2020, China proposed the country’s dual carbon goals of peaking carbon emissions by 2030 and achieving carbon neutrality by 2060. Under the dual carbon goals, the low-carbon transformation has become an important development direction for Chinese ports. Taking eight ports in China’s Bohai-rim port group as an example, this study adopts the Slacks-Based Measure (SBM) model to evaluate the port efficiency considering the environmental factor of carbon dioxide (CO2) emissions. The results show that the average scale environmental efficiency of the eight ports during 2005-2020 is the highest, followed by local pure technical environmental efficiency and global technical environmental efficiency. The efficiency values of each port under different environmental efficiency categories vary greatly. Overall, each port is in a state of environmental inefficiency. From port technology, input-output optimization, supervision, and management of relevant departments, recommendations for improving the environmental efficiency of ports under the dual carbon goals are put forward

Laser frequency stabilization and photoacoustic detection based on the tapered fiber coupled crystalline resonator

We demonstrate laser frequency stabilization using a high-Q MgF2 crystalline whispering gallery mode resonator coupled with a tapered fiber. We discovered that the tapered fiber, acting as a microcantilever, exhibits mechanical resonance characteristics that is capable of transmitting acoustic perturbations to the frequency locking loop. Both experimental and theoretical investigations into the influence of external acoustic waves on the coupling system were conducted. After acoustic isolation, the locked laser exhibits a minimum frequency noise of 0.4Hz2/Hz at 7kHz and an integral linewidth of 68Hz (0.1s integration time). Benefiting from the ultralow frequency noise of the stabilized laser, it achieves a minimum noise equivalent acoustic signal level of 4.76*10-4 Pa/Hz1/2. Our results not only facilitate the realization of ultralow noise lasers but also serves as a novel and sensitive photoacoustic detector

Hainan sport tourism development—A SWOT analysis

Hainan, as a popular tourism destination, is well-promoted by the Chinese central government. In particular, both central and local governments encourage Hainan’s sport tourism-related professionals to develop sport tourism as one of the most important tourist activities in Hainan. However, previous research has not reported on Hainan’s sport tourism strengths, weaknesses, opportunities, and threats as a tourism destination or a sports event host. This study uses SWOT analysis to identify the strengths, weaknesses, opportunities, and threats in the context of Hainan’s sport tourism development. A total of 12 dimensions, including branding, culture, finance, infrastructure, location, market, nature, policy, product, specialty, sustainability, and tourist were generated from our data analysis. In addition, a total of five future directions, including emphasizing event-oriented sport tourism, prioritizing sport motivation, identifying major sport tourism markets, making the rational use of sport tourism resources, and nurturing sport culture, are recommended as a result of this study

Comprehensive Effect of Different Crop Loads on the ‘Shine Muscat’ Quality

To investigate the effects of different crop loads on the overall quality of 'Shine Muscat', this study was conducted to regulate the crop loads by berry thinning and to evaluate the sugar, acid and phenolic contents, antioxidant activity and economic benefits of the berries. The results showed that the average berry weight at low crop loads increased significantly, glucose and fructose contents increased significantly, and tartaric and malic acid contents decreased significantly, leading to a significant increase in the sugar-acid ratio of the berries (P<0.05). The phenolic content at low crop loads also increased significantly and the antioxidant capacity of the berries was significantly better than the other treatment groups (P<0.05). The excellent overall quality of berries at low crop loads made them more economically profitable. Thus, better grape quality could be achieved by precisely controlling the berry crop load