基于LBSN动态异构网络的时间感知兴趣点推荐

随着基于位置社交网络(Location-Based Social Network,LBSN)的快速发展,兴趣点(Point-Of-Interest,POI)推荐可以帮助人们发现有趣的并吸引人的位置。针对签到数据的稀疏性和用户兴趣的动态性等挑战性问题,提出了基于LBSN动态异构网络的时间感知兴趣点推荐算法。在LBSN异构网络模式中增加会话节点类型。通过动态元路径,在用户和兴趣点语义关系之间有效地融入时间信息、位置信息和社交信息等。设置了用户-兴趣点之间的动态元路径集,并提出了动态路径实例的偏好度计算方法。采用矩阵分解模型对不同动态偏好矩阵进行矩阵分解。根据不同动态元路径的用户特征矩阵和兴趣点特征矩阵,获取用户在目标时间访问兴趣点的推荐列表。实验结果表明,与其他兴趣点推荐方法相比,所提方法在兴趣点推荐精确度上取得了较好的推荐结果,具有良好的应用前景。     

Understanding consumer resistance to the consumption of organic food. A study of ethical consumption,purchasing, and choice behaviour

Although the demand for organic food is growing globally, the mainstream consumption of organic food is far less. The present study attempts to understand the underlying reasons for consumer resistance toward consuming organic food using the theoretical framework of innovation resistance theory (IRT). The study further examines the association between different consumer barriers and purchase decisions (purchase intentions, ethical consumption intentions, and choice behaviour) at different levels of buying involvement and environmental concerns. The collected data, consisting of 452 consumers, were analyzed by structural equation modeling approach. The results showed that value barrier shared a negative association with purchase intentions and ethical consumption intentions. Ethical consumption and purchase intention were found to have a direct influence on choice behaviour. Additionally, the relationship between ethical consumption intention and choice behaviour is mediated by purchase intention. However, no significant differences have emerged based on the level of buying involvement and environment concerns. The findings of the study provide insight into public policymakers, marketers, suppliers, and consumer associations by enhancing their current understanding of buying behaviour of the growing organic food community.     

Systematic study of Nd~(3+) on structural properties of ZnO nanocomposite for biomedical applications; in-vitro biocompatibility,bioactivity, photoluminescence and antioxidant properties

Owing to the inconformity in ionic radius between Nd~(3+) and Zn~(2+), the successful incorporation of Nd~(3+) ion into the ZnO nanocrystals still remains a great challenge. In the present study various doping ratios containing 1 wt%, 5 wt%, 7 wt% and 10 wt% of Nd~(3+) doped ZnO nanoparticles(Nd/ZnO NPs) were synthesized in which a bio-layer caped the NPs. SEM/EDX analysis was performed on the ZnO and Nd/ZnO NPs. In addition, the as-synthesized NPs were characterized using X-ray diffraction(XRD), dynamic light scattering(DLS), differential reflectance spectroscopy(DRS) and photoluminescence(PL) spectroscopy.The average size of Nd(5 wt%)/ZnO NPs was in the range of 6.22 and 15 e18 nm based on XRD and SEM techniques, respectively. The measured band gap values for pure ZnO and Nd/ZnO NCs with doping ratios of 1 wt%, 5 wt%, 7 wt% and 9 wt% were equal to 3.46, 3.26, 3.05, 3.25 and 3.29, respectively. After inhalation, nanoparticles first interact with lung surfactant system and accordingly their toxic effects will appear on lungs cells such as A549 cell line. The effect of Nd/ZnO NPs to interact by human A549 cell line was evaluated by means of cell viability test. According to cell viability test the concentrations of 0.3 and 0.5 mg/mL of Nd/ZnO NPs induce a low toxicity. The present study shows that these toxic effects of Nd/ZnO NPs can be rectified by capping its surface via the addition of a bio-layer around particles in order to prevent them from interacting A549 cell line.     

Postural strategy identification during drilling task for different materials and heights: Ergonomic risk assessment

Drilling is an activity carried out in both professional and domestic environments. In this context, knowing the postural strategies used by users is a challenge. The objective of this study is twofold: 1) to identify the different possible strategies for performing a piercing while characterizing them through quantitative biomechanical parameters related to the task; 2) to propose an evaluation of the ergonomic risks incurred by the users for each of the observed strategies. Thus, fourteen subjects carried out a drilling activity at two different heights and for two types of materials. The position of the gravity center projection in relation to the sustentation polygon as well as the angle between the axis connecting the two feet and the antero-posterior axis (drilling axis) were used to identify the different postural strategies. Three strategies respectively called “Inter-feet”, “Left foot” and “External strategy” and three sub-strategies were identified. Each has been characterized through the duration and the average and maximum forces applied during the drilling phase. Two of them, 0–30° and 30–60° Inter-feet strategies covered about 75% of the trials. Despite the presence of a lower score for the 30–60° and 60–90° External strategies, the ergonomic analysis through the Rapid Upper Limb Assessment revealed that regardless of the strategy used, the postures adopted presented risks of developing musculoskeletal disorders. Thus, the drilling activity must be considered with care.Relevance to industryThe identification and characterization of postural strategies is particularly interesting to better understand the organization of the drilling task and thus optimize productivity while ensuring operator safety.     

Prediction of risk factors of cyberbullying-related words in Korea: Application of data mining using social big data

The study examined a decision tree analysis using social big data to conduct the prediction model on types of risk factors related to cyberbullying in Korea. The study conducted an analysis of 103,212 buzzes that had noted causes of cyberbullying and data were collected from 227 online channels, such as news websites, blogs, online groups, social network services, and online bulletin boards. Using opinion-mining method and decision tree analysis, the types of cyberbullying were sorted using SPSS 25.0. The results indicated that the total rate of types of cyberbullying in Korea was 44%, which consisted of 32.3% victims, 6.4% perpetrators, and 5.3% bystanders. According to the results, the impulse factor was also the greatest influence on the prediction of the risk factors and the propensity for dominance factor was the second greatest factor predicting the types of risk factors. In particular, the impulse factor had the most significant effect on bystanders, and the propensity for dominance factor was also significant in influencing online perpetrators. It is necessary to develop a program to diminish the impulses that were initiated by bystanders as well as victims and perpetrators because many of those bystanders have tended to aggravate impulsive cyberbullying behaviors.     

Effects of multiple-try feedback and question type during mathematics problem solving on performance in similar problems

In a study of mathematics problem solving, the effect of providing multiple-try feedback on later success in solving similar problems was examined. Participants solved mathematics problems that were presented as either multiple-choice or open-ended questions, and were provided with one of four types of feedback: no feedback (NF), immediate knowledge of the correct response (KCR), multiple-try feedback with knowledge of the correct response (MTC), or multiple-try feedback with hints after an initial incorrect response (MTH). Results showed that gains in performance were larger in the open-ended than multiple-choice condition. Furthermore, gains under NF and KCR were similar, gains were larger under MTC than KCR, and gains were larger under MTH than MTC. The implications of these results for the design of assessments for learning are discussed.     

Secondary school educators' perceptions and practices in handling cyberbullying among adolescents: A cluster analysis

School educators play an important role in cyberbullying management. Since scarce earlier research indicated low perceived competence of school educators in handling cyberbullying, more insight is needed in what determines their actions and how to improve these practices. This study assessed school educator practices, their perceptions and context factors from a behavior change theoretical framework, and investigated educator clusters related to this. An online survey was conducted among 451 secondary school educators (teachers, principals, school counselors). School educators mostly used recommended actions (i.e. conversations with pupils, enlisting professionals for support, parental involvement, providing supportive victim advice). Four educator clusters were identified: ‘referrers’ (65%), ‘disengaged’ educators (14%), ‘concerned’ educators (12%) and ‘use all means’ educators (9%). The first two clusters were less adept at handling cyberbullying and comprised mostly teachers, particularly indicating a need for training teachers. Our findings show a need for tailored educator training, e.g. by job position, gender, school size and grade. The behavior change theoretical framework can help target educators' particular needs.     

Putting yourself in someone else's shoes: The impact of a location-based,collaborative role-playing game on behaviour

The goal of this study was to probe the effectiveness of a mobile game-based learning approach in modifying behavioural outcomes and competence. The experiment was set against the background of low rates of laymen providing CPR during sudden cardiac arrests. A post-test control group design was used to contrast and evaluate the effects of the two different types of learning. Two hundred two students were randomly assigned to two conditions, a game-based variant simulating an emergency situation (experimental group), and an instruction-based approach (control group). After the intervention participants completed a questionnaire assessing self-prediction, self-efficacy, attitude, subjective norm, empathy and competence. The largest arguably significant difference between the two groups showed in self-prediction and capacity beliefs. Results further revealed a positive relationship between self-prediction and the variables attitude and self-efficacy. The type of scenario did not translate into the other concepts we assessed, though, and results were inconclusive regarding the effectiveness of the type of learning scenario and CPR knowledge. We explain the small effect size partly by the experimental procedure and the design of the game intervention, which is discussed in the course of this article.     

High purity H2 production from sorption enhanced bio-ethanol reforming via sol-gel-derived Ni–CaO–Al2O3 bi-functional materials

Catalytic steam reforming of renewable bio-oxygenates coupled with in-situ CO₂ capture is a promising option for sustainable H₂ production. The current work focuses on high purity H₂ production over Ni–CaO–Al₂O₃ bi-functional materials via sorption enhanced steam reforming of ethanol (SEESR). To ensure the uniform distribution of catalytic sites (Ni), adsorptive sites (CaO) and stabilizer (Al₂O₃) in the bi-functional materials, a citrate sol-gel synthetic route was employed. These materials were characterized by XRD, N₂ physical adsorption, SEM, TG and TPR techniques. It was revealed that the existence of CaO in bi-functional materials could not only in-situ remove CO₂, but also play the role of inhibiting the formation of harmful spinel phase. The stabilizing role of Al component against capacity decay was confirmed, whereas the presence of Ni ions had a negative effect on the cycle CO₂ uptake. The sample of Ni/Al/Ca-85.5 possessed large specific surface area, abundant porosity with fluffy morphology, and thereby, exhibited the best CO₂ sorption capacity during 20 carbonation/calcination cycles. The highest H₂ concentration of 96% was obtained through the SEESR during the pre-breakthrough period when the Ni/Al/Ca-85.5 was employed. Over the optimized bi-functional material, the effect of operating conditions on the SEESR was investigated and the results indicated that temperature of 600 °C, reaction liquid space velocity of 0.05 ml/min and steam/ethanol ratio of 4 were the suitable conditions. After 10 cycles, the bi-functional material of Ni/Al/Ca-85.5 also showed the best performance, with a H₂ purity of about 90% and pre-breakthrough time of 18 min, conforming the high potential of this material for SEESR process.