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Aim Spatial dynamics and habitat connectivity affect community composition and diversity in many ecosystems. For many decades, diversity patterns in riverine ecosystems were thought to be related to local environmental conditions. Recent theoretical work, however, suggests that diversity in rivers is strongly affected by dispersal along the dendritic landscape structure and that environmental conditions are intrinsically linked to the network position. In this study we tested hypotheses on network position by relating river network geometry and connectivity to multi-level biodiversity patterns across large scales. Location Three major alpine drainage basins in Switzerland were studied (Rhine, Rhone, Ticino), extending over an elevational gradient of > 2500 m and covering a total area of 41,285 km 2 . Methods We sampled all may-, stone- and caddisfly species at 217 sites which representatively cover the three river networks. Using generalized additive models, we related diversity patterns in aquatic insects to centrality within the network as a direct river network property, and to catchment area and elevation, which are related to network position. Results Centrality within the river network, and catchment area and elevation had significant and interacting effects on α-diversity and community similarity. Alpha diversity was lowest in peripheral headwaters and at high elevations. Species richness generally increased with increasing catchment area. Well-connected, central communities within the river network had greater α-diversity than more peripheral communities did. Elevation was a strong predictor of α-diversity, with the most diverse communities found at mid-elevation sites. Community similarity decreased with increasing along-stream distance between sites. Main conclusions Our results highlight the fact that diversity patterns of aquatic insects in river systems are related to local factors such as elevation, but interact with network properties and connectivity along waterways, and differ among insect orders. These findings are consistent with dispersal-limited processes and indicate the riverine diversity should be addressed and protected taking the river network structure into account.

As the genome carries the historical information of a species’ biotic and environmental interactions, analyzing changes in genome structure over time by using powerful statistical physics methods (such as entropic segmentation algorithms, fluctuation analysis in DNA walks, or measures of compositional complexity) provides valuable insights into genome evolution. Nucleotide frequencies tend to vary along the DNA chain, resulting in a hierarchically patchy chromosome structure with heterogeneities at different length scales that range from a few nucleotides to tens of millions of them. Fluctuation analysis reveals that these compositional structures can be classified into three main categories: (1) short-range heterogeneities (below a few kilobase pairs (Kbp)) primarily attributed to the alternation of coding and noncoding regions, interspersed or tandem repeats densities, etc.; (2) isochores, spanning tens to hundreds of tens of Kbp; and (3) superstructures, reaching sizes of tens of megabase pairs (Mbp) or even larger. The obtained isochore and superstructure coordinates in the first complete T2T human sequence are now shared in a public database. In this way, interested researchers can use T2T isochore data, as well as the annotations for different genome elements, to check a specific hypothesis about genome structure. Similarly to other levels of biological organization, a hierarchical compositional structure is prevalent in the genome. Once the compositional structure of a genome is identified, various measures can be derived to quantify the heterogeneity of such structure. The distribution of segment G+C content has recently been proposed as a new genome signature that proves to be useful for comparing complete genomes. Another meaningful measure is the sequence compositional complexity (SCC), which has been used for genome structure comparisons. Lastly, we review the recent genome comparisons in species of the ancient phylum Cyanobacteria, conducted by phylogenetic regression of SCC against time, which have revealed positive trends towards higher genome complexity. These findings provide the first evidence for a driven progressive evolution of genome compositional structure.

The detailed lithospheric structure of South China is the basis for the understanding of tectonic processes of eastern China. Specifically, two essential issues in the study of lithospheric structure are the thermal and compositional structures, which are usually derived from either geophysical or geochemical observations. However, inversions from single geophysical or geochemical datasets have certain limitations, making it necessary to develop joint inversions of geophysical, geochemical and petrological datasets. In this paper, through thermodynamic simulation and probabilistic inversion, we inverted multiple datasets including topography, geoid height, surface heat flow and surface wave dispersion curves for the 3D lithospheric thermal and compositional structure of South China. The results reveal a thin (< 100 km) and flat LAB beneath the South China Fold System Block and the lower Yangtze Craton. Also, we found that the lithospheric mantle is primarily composed of saturated peridotite, indicating that the ancient refractory lithospheric mantle has been replaced by new materials. The dominant dynamic mechanism for lithospheric thinning in eastern South China may be the flat subduction of ancient Pacific slab, while thermal erosion may have also played a significant role. In contrast, the LAB depth beneath the Sichuan Basin is much thicker (> 200 km), suggesting that the thick and cold craton lithospheric roots are retained. There may exist a discontinuous interface beneath the Sichuan Basin, with the saturated lower layer thicker than the refractory upper layer. As a result, the lithospheric mantle of the Sichuan Basin and surrounding regions is mainly composed of saturated and transitional peridotite.

Aim Dendritic ecological networks (DENs), such as river systems, combine features that challenge the traditional conceptual views and empirical approaches applied to metacommunities. As a result of their dendritic branching geometry and stream flow directionality, they are strongly hierarchical and asymmetrical. We analysed the metacommunity structure of benthic diatoms in a large-scale river system with the aim of evaluating the importance of potential causal influences. Furthermore, we hypothesized that metacommunities of diatoms that are strongly attached to their substrata show a different spatial structure than metacommunities of other, more weakly attached diatoms. Location The study was carried out in the Dong River, a 32,275 km 2 subtropical river network located in southern China. Methods We surveyed benthic diatom communities during three seasons (dry, intermediate and wet). Using partial redundancy analysis, we partitioned community variation among environmental models and different spatial eigenfunction models to evaluate the influence of alternative dispersal pathways (overland versus water course dispersal), stream directionality, man-made dams and diatom functional traits on diatom metacommunity structure. Results Models based on hydrological connections and water directionality represent spatial patterns better than overland distances, suggesting that the dynamics of benthic diatom metacommunities are mainly confined to the river network and influenced by the prevailing water flow. We found significant effects of man-made dams on the spatial structure of important limnological variables and diatom metacommunity structure. The metacommunity of strongly attached diatoms also showed a weaker signature of flow directionality than that of other growth forms, especially in seasons with high water levels. Main conclusions We conclude that the consideration of among-site connectivity, flow directionality and species traits is key to a better understanding of the spatial ecology of passively dispersing microbial organisms in river systems.

This investigation focused on obtaining samples from ceramic composite materials, based on the ZrO2–20%Al2O3 system, using the additive layer-by-layer fusion technology for thermoplastic systems. The structure and phase composition of the initial powders were studied, experimental samples were produced, and the structure and properties of the experimental samples that were obtained using additive technologies were analysed. The measured static bending strength of the samples was 450 ± 70 MPa, microhardness was 14 GPa, and the elasticity modulus was 280 ± 25 GPa. The strength of these samples are slightly inferior to that of similar materials, obtained using Ceramic Injection Molding technology because our samples were characterised by the residual porosity of about 15%.

Contrapuntal direction—the principle that certain progressions may only occur through the motion of the contrapuntal voice towards a stable tenor—is a previously unrecognized implication of the teaching of the theorist and composer Johannes Tinctoris. Although Tinctoris’s interval successions are commonly the same whichever voice is the tenor, Tinctoris omits a small number of oblique progressions where the tenor would move. Although I will not investigate possible reasons for this omission, examples will show that when the missing progressions occur in repertoire, these can be explained by a reappraisal of the contrapuntal functions of the voices. The results extend Julie Cumming’s concept of the “movable module” and demonstrate its presence in music of the 1460s and 1470s. This principle emerges directly from a computer-assisted attempt to connect Tinctoris’s counterpoint with late-fifteenth century composition. Through its ability to recognise tenor function within a voice pair, to identify instances where the tenor function may have moved, or to mark voices that do not form a contrapuntal pair, directional analysis is able both to identify faulty analytical assumptions around voice pairing and to act as a validator of general theories of fifteenth-century compositional structure.

Despite their unprecedented success, artificial neural networks suffer extreme opacity and weakness in learning general knowledge from limited experience. Some argue that the key to overcoming those limitations in artificial neural networks is efficiently combining continuity with compositionality principles. While it is unknown how the brain encodes and decodes information in a way that enables both rapid responses and complex processing, there is evidence that the neocortex employs sparse distributed representations for this task. This is an active area of research. This work deals with one of the challenges in this field related to encoding and decoding nested compositional structures, which are essential for representing complex real-world concepts. One of the algorithms in this field is called context-dependent thinning (CDT). A distinguishing feature of CDT relative to other methods is that the CDT-encoded vector remains similar to each component input and combinations of similar inputs. In this work, we propose a novel encoding method termed CPSE, based on CDT ideas. In addition, we propose a novel decoding method termed CPSD, based on triadic memory. The proposed algorithms extend CDT by allowing both encoding and decoding of information, including the composition order. In addition, the proposed algorithms allow to optimize the amount of compute and memory needed to achieve the desired encoding/decoding performance.

Aim The delineation of regions is a critical procedure in biogeography, but there is still no consensus about the best approach. Traditionally, a compositional dissimilarity index and a clustering algorithm are used to partition locations into regions. However, the choice of index and algorithm may have a profound impact on the final result, particularly when locations display different levels of species richness and when they are nested within each other. Our objective was to estimate the influence of species nestedness among locations on the delineation of biogeographical regions. Location As a case study, we used coral reef fishes (families Chaetodontidae, Pomacentridae and Labridae) from the Indo-Pacific, where a large richness gradient extends, often as a series of nested assemblages, from the species-rich Indo-Australian Archipelago (Coral Triangle) to species-poor peripheral locations. Methods We used the turnover and nestedness components of the Sørensen and Jaccard dissimilarity indices to estimate the effect of nestedness on the delineation of biogeographical regions. In addition, we compared the results with those obtained using a parsimony analysis of endemicity (PAE). Results Low Mantel correlation values revealed that the PAE method assembled locations in a very different way than methods based on dissimilarity indices for Indo-Pacific coral reef fishes. We also found that nestedness mattered when delineating biogeographical units because, for both the Sørensen and the Jaccard indices, reef fish assemblages were grouped differently depending on whether we used the turnover component of each index or the complete index, including the nestedness component. The turnover component ignored variation in species richness attributable to differences in habitat area between locations, and permitted a delineation based solely on species replacement. Main conclusions We demonstrate that the choice of the component used to measure dissimilarity between species assemblages is critical, because it may strongly influence regional delineations, at least for Indo-Pacific coral reef fishes. We conclude that the two components of the dissimilarity indices can reveal complementary insights into the role that history may have played in shaping extant patterns of biodiversity.

Human gut microflora includes three enterotypes and composes the largest part of the whole microbiome. Because gut microflora play a crucial role in health and disease, knowing the microbial composition of the gut microbiome is an important task. Currently, the gut microbiome composition in the Kazakhstani population is poorly understood. Therefore, we studied the phylogenetic composition and types of the gut microbiome in Kazakhstani women and stratified the data by age. Female subjects were divided into three groups: six young (<44 years old), eighteen middle-aged (50-70 years old), and six elderly (>90 years old). For the gut microbiome composition analysis, the 16S rDNA locus was amplified, ligated into high copy plasmid vectors, and sequenced. We observed that two gut microbiome types, Phyla Bacteroidetes and Firmicutes, were age independent. However, there were significant differences in species composition between groups that can be attributed to age. The highest species diversity occurred in the middle-aged group, which subsequently decreased in the elderly group.

Distinct performances of the same song can mean very different things. Yet the meaning of the song may be fixed. Gracyk's immediate purpose is to show how the interplay of semantics and pragmatics generates different meanings in different performances. Context-dependent aspects of a song's meaning should not be confused with context-dependent aspects of a performance's meaning. Gracyk's more general purpose is to advance our understanding of musical meaning. Musical performances are rich in meaning because semantic information, contingently associated with a musical structure, generates myriad possibilities for generating pragmatic contextual supplementation of the work during its performances.