As a special branch of global trade, the trade of agricultural products has an important impact on food security and the environment. In this paper, we studied international trade network of agricultural products from 2000 to 2016 as a whole and in part. We explored the overall characteristics of the network, analyzed the evolution of communities and identified core countries of the communities. The results show that the structure of the trade network became increasingly complex and the trade relations became closer over time. There were four major communities in the network, whose primary core countries were Germany, the United States, Brazil, and China. Since 2007, the community represented by China has disappeared, and the community pattern of the network has been in a three-pillar state and basically stable. We discuss the actual roles of certain trading countries, the formation of communities and the impact of economic events on agricultural products trade. This paper reveals the underlying patterns of the agricultural products trade and provides a way to track its evolution over time.

Two Gram-stain-negative, straight rods, non-motile, asporogenous, catalase-negative and obligately anaerobic butyrate-producing strains, HLW78^T and CYL33, were isolated from faecal samples of two healthy Taiwanese adults. Phylogenetic analyses of 16S rRNA and DNA mismatch repair protein MutL (mutL) gene sequences revealed that these two novel strains belonged to the genus Faecalibacterium. On the basis of 16S rRNA and mutL gene sequence similarities, the type strains Faecalibacterium butyricigenerans AF52-21^T(98.3–98.1 % and 79.0–79.5 % similarity), Faecalibacterium duncaniae A2-165^T(97.8–97.9 % and 70.9–80.1 %), Faecalibacterium hattorii APC922/41-1^T(97.1–97.3 % and 80.3–80.5 %), Faecalibacterium longum CM04-06^T(97.8–98.0% and 78.3 %) and Faecalibacterium prausnitzii ATCC 27768^T(97.3–97.4 % and 82.7–82.9 %) were the closest neighbours to the novel strains HLW78^T and CYL33. Strains HLW78^T and CYL33 had 99.4 % both the 16S rRNA and mutL gene sequence similarities, 97.9 % average nucleotide identity (ANI), 96.3 % average amino acid identity (AAI), and 80.5 % digital DNA–DNA hybridization (dDDH) values, indicating that these two strains are members of the same species. Phylogenomic tree analysis indicated that strains HLW78^T and CYL33 formed an independent robust cluster together with F. prausnitzii ATCC 27768^T. The ANI, AAI and dDDH values between strain HLW78^T and its closest neighbours were below the species delineation thresholds of 77.6–85.1 %, 71.4–85.2 % and 28.3–30.9 %, respectively. The two novel strains could be differentiated from the type strains of their closest Faecalibacterium species based on their cellular fatty acid compositions, which contained C_18 : 1  ω7c and lacked C_15 : 0 and C_17 : 1  ω6c, respectively. Phenotypic, chemotaxonomic and genotypic test results demonstrated that the two novel strains HLW78^T and CYL33 represented a single, novel species within the genus Faecalibacterium, for which the name Faecalibacterium taiwanense sp. nov. is proposed. The type strain is HLW78^T (=BCRC 81397^T=NBRC 116372^T).

The representation of vector data at variable scales has been widely applied in geographic information systems and map-based services. When the scale changes across a wide range, a complex generalization that involves multiple operations is required to transform the data. To present such complex generalization, we proposed a matrix model to combine different generalization operations into an integration. This study was carried on a set of river network data, where two operations, i.e., network pruning accompanied with river simplification, were hierarchically constructed as the rows and columns of a matrix. The correspondence between generalization operations and scale, and the scale linkage of multiple operations were also explicitly defined. In addition, we developed a vario-scale data structure to store the generalized river network data based on the proposed matrix. The matrix model was validated and assessed by a comparison with traditional methods that conduct generalization operations in sequence. It was shown that the matrix model enabled complex generalization with good generalization quality. Taking advantage of the corresponding vario-scale data structure, the river network data could be obtained at any arbitrary scale, and the vario-scale representation was achieved across a wide scale range.

Mapping water quality change is helpful in the study of the water environment of a region. Using visual methods, interpretation of water condition and pollution issues can be intuitive and easy to understand. In this paper, we present a map to represent the spatial and temporal variation of water quality change in the Yangtze River during the period from 2006 to 2015. The calendar view was developed to explore the water quality condition and water pollutants for sections of the Yangtze River. A “W” construction was proposed to arrange the weekly water quality data in a continuous logic, and qualitative colors were designed to identify the change in major pollutants throughout the period. This map provides a promising visual analytical approach to investigate the water quality status and reveal the spatial and temporal patterns of water quality change in the Yangtze River.

With the rapid development of 3D technology currently, in particular, on the context of building smart cities, a number of novel 3D geo-visualizations have been advanced, such as immersive maps, panoramic location-based service, and augmented reality systems. These visualizations refer to not only the technological aspects but also the user’s abilities to cognize and make used of presented information(Herman et al., 2018, Šašinka et al., 2018, Kubíček et al., 2019). Note the existing researches usually concentrate on the presentation parameters and the usability of consequential visualizations in actual tasks(Lokka and Coltekin, 2016, Roth et al., 2017, Lokka and Coltekin, 2019). The influence of user factors on 3D spatial perception which is essential for 3D geo-visualization applications still remains unclear.In our study, we explored the user differences of spatial perception in 3D geo-visualization in contrast to that in real scene. The research questions were specified as follows: (1) How does the user factors, i.e. gender, age, academic background, mental rotation ability, and abstract reasoning ability, influence the user performance in spatial tasks related to distance perception, height perception, and environmental perception(Siegel and White, 1975)? (2) Is the user perception ability in 3D geo-visualization consistent with that in real scene?This study is an exploratory research. Series of experiments were designed based on questionnaire survey, mental mapping and eye-tracking techniques. On the one hand, a questionnaire, a Mental Rotation Test (MRT) and an Abstract Reasoning Test (ART) were conducted to figure out the user profiles, namely the personal information of the participants. On the other hand, a list of spatial tasks were instructed both in a 3D geo-visualization and in a real scene. During the procedure, participants were requested to answer several questions, in addition, their eye movements were recorded using an eye tracker. The participants were also asked to draw a mental map with hands to recall the layout of scene and their travelling path. After all these experiments, the participants’ spatial perception ability were assessed by calculating the accuracy and efficiency of their performance. Consequentially, the significance of participant differences were investigated through a set of quantitative analysis.The experimental process refers to three stages: Firstly the questionnaire including MRT and ART, secondly spatial performance in a virtual 3D scene, and thirdly comparative spatial performance in the real scene. For the stage of virtual 3D scene, an interactive 3D geo-visualization platform was developed, so that the users can freely switch the Line of Sight (LOS) and Angle of Field (AOF). For the stage of real scene, a real-world area which is isomorphic to the virtual 3D scene was designated as the test filed. Forty participants were recruited from three universities in Wuhan, China. According to our study, a few interesting results can be obtained:(1) In general, there are significant user differences in spatial perception with respect to the visual style, i.e. 3D geo-visualization and real scene. The participants expressed higher level of environmental perception in real scene thanin 3D geo-visualization (r_3d=4.333, r_real=4.001, Sig.=0.044). The participants provided mental maps of real scenein more details than that of the 3D geo-visualization. Meanwhile, they perform better way-finding behaviour with shorter distance moving and less corner turning in real scene.(2) By measuring the single influence of user characters, it is indicated that orientation idiom has significant effect onuser’s mental rotation ability. The participants who use front-back-left-right as their orientation idioms trend tohave higher correct accuracy in MRT, while those using north-south-east-west as their orientation idiom seem tohave lower correct accuracy (r_fblr=19.64, r_nsew=12.46, Sig.=0.030, Independent-samples Mann-Whitney U Test).When we group participants with the spatial reference frameworks of self-centred reference, fixed reference andcoordinative reference(Byrne et al., 2007), it is easy to find that the type of spatial reference frameworks hasrelative significant effect on distance perception in 3D geo-visualization. Those participants using self-centredreference show the highest accuracy rate, while the ones using coordinative reference show relative lowestaccuracy rate(r_selfCent=22.42, r_fixed=15.47, r_coord=13.43, Sig.=0.056, Independent-samples Kruskal-Wallis Test). Nevertheless, other user factors, including academic background (students of cartography or non-cartography), age (from 21–24) and activity scope, show no significant influence on spatial perception in 3D geo-visualization as well as in real scene.(3) Looking into the combined influence of multiple factors, there is a significant interaction between gender andorientation idioms on the environmental perception in 3D geo-visualization environment, but neither of themshows a significant main effect (Sig._gender=0.817, Sig._oriIdio=0.423, Sig._combined=0.037). The female participantsusing north-south-east-west orientation idiom have higher level of environmental perception than those using front-back-left-right (Sig.=0.064), however, the male participants show no significant difference no matter whichorientation idiom they use.Spatial reference framework and orientation idiom have similar significant interaction on distance perception inreal scene, furthermore, the orientation idiom presents a relative significant main effect (Sig._spatialRef=0.882,Sig._oriIdio=0.071, Sig._combined=0.038). The participants who use self-centred reference and orientation idiom ofnorth-south-east-west have higher accuracy rate than the ones using self-centred reference and orientation idiom offront-back-left-right (Sig.=0.007).In addition, gender and spatial reference...