A novel simplification method for GPS trajectory is presented in this paper. Trajectory simplification can greatly improve the efficiency of data analysis (e.g., querying, clustering). Based on the observation of information content contained by sampling data, we assume that (1) the sampling points on the boundary of MBR (Minimum Bounding Rectangle) contain more information content, (2) the bigger the area of MBR is, the more the points should be stored. We applied these two assumptions in our method to simplify trajectory online. Two main components of this method (i.e., divide/merge principle and selection strategy), are elaborated in the paper. Moreover, we define a new error metric-enclosed area metric-to evaluate the accuracy of simplified trajectories, which is proven more robust against the uncertainty of GPS. To implement this measure, we devise a practical algorithm of area calculation for self-intersecting polygons. Through comparing with other methods in a series of experiments over huge dataset, our method is proven effective and efficient.

No abstract

Background: Driven by accelerating population aging and migration, the number of older migrants has increased rapidly in China. Those who moved to cities to look after grandchildren were referred to as the migrant elderly following children (MEFC). This study aims to examine the relationship between sense of belonging and loneliness and explore the moderating effect of migration pattern among the MEFC in China. Methods: The study included 656 MEFC aged 60 years and above. Loneliness was evaluated by the eight-item University of California Los Angeles Loneliness Scale (ULS-8). Sense of belonging and migration pattern were measured using a self-designed questionnaire. Hierarchical multiple regression was conducted to test the proposed association and moderating effect. A margins plot was introduced to illustrate this effect. Results: The average ULS-8 score was 12.82 ± 4.05, revealing a low level of loneliness. A weak sense of belonging was related with a higher level of loneliness (β = 0.096, p = 0.014). Migration pattern was found to exacerbate this association (β = 0.138, p = 0.026), especially for the elderly who migrated across provinces. Conclusions: Sense of belonging was correlated with loneliness, and the moderating role of migration pattern was established. Both policymakers and the adult children of inter-provincial migrant elderly should focus on this special subgroup.

No abstract

Popular real-time public events often cause upsurge of traffic in Twitter while the event is taking place. These posts range from real-time update of the event's occurrences highlights of important moments thus far, personal comments and so on. A large user group has evolved who seeks these live updates to get a brief summary of the important moments of the event so far. However, major social search engines including Twitter still present the tweets satisfying the Boolean query in reverse chronological order, resulting in thousands of low quality matches agglomerated in a prosaic manner. To get an overview of the happenings of the event, a user is forced to read scores of uninformative tweets causing frustration. In this paper, we propose a method for multi-tweet summarization of an event. It allows the search users to quickly get an overview about the important moments of the event. We have proposed a graph-based retrieval algorithm that identifies tweets with popular discussion points among the set of tweets returned by Twitter search engine in response to a query comprising the event related keywords. To ensure maximum coverage of topical diversity, we perform topical clustering of the tweets before applying the retrieval algorithm. Evaluation performed by summarizing the important moments of a real-world event revealed that the proposed method could summarize the proceeding of different segments of the event with up to 81.6% precision and up to 80% recall.

No abstract

No abstract

The NAD(P)-dependent alcohol dehydrogenase (ADH) gene was cloned from Gluconobacter frateurii NBRC 3264 and expressed in Escherichia coli BL21 star (DE3). The expressed enzyme was purified and the characteristics were investigated. The results showed that this ADH can convert allitol into D-allulose (D-psicose), which is the first reported enzyme with this catalytic ability. The optimum temperature and pH of this enzyme were 50°C and pH 7.0, respectively, and the enzyme showed a maximal activity in the presence of Co2+. At 1 mM Co2+ and allitol concentrations of 50, 150, and 250 mM, the D-allulose yields of 97, 56, and 38%, respectively, were obtained after reaction for 4 h under optimal conditions, which were much higher than that obtained by using the epimerase method of about 30%.