Structural Complexity I

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The structural complexity of software an experimental test Abstract: This research examines the structural complexity of software and, specifically, the potential interaction of the two dominant dimensions of structural complexity, coupling and cohesion. Analysis based on an information processing view of developer cognition results in a theoretically driven model with cohesion as a moderator for a main effect of coupling on effort.

An empirical test of the model was devised in a software maintenance context utilizing both procedural and object-oriented tasks, with professional software engineers as participants.

Uranyl-oxide hydroxy-hydrate minerals: their structural complexity and evolution trends

The results support the model in that there was a significant interaction effect between coupling and cohesion on effort, even though there was no main effect for either coupling or cohesion. The implication of this result is that, when designing, implementing, and maintaining software to control complexity, both coupling and cohesion should be considered jointly, instead of independently.

By providing guidance on structuring software for software professionals and researchers, these results enable software to continue as the solution of choice for a wider range of richer, more complex problems. Article :. Date of Publication: 12 December DOI: The same approach was used to determine the set of predictor variables that better explained the variability of total abundance and richness of fishes, but using Euclidean distances to construct the similarity matrix.

Coral colonies exhibited a high variability in their geometrical and biological characteristics, further indicating that the structure of the fish habitat measured features changes from one colony to the other Table 1 and Fig. For example, colony length and height ranged from 50 to cm and from 27 to 80 cm, respectively. Max maximum value. A total of fish belonging to 11 families and 20 species were found inhabiting Acropora cervicornis colonies at our study site.

Thus, the results indicated that there was not a single common group of fishes associated with all the colonies.

Levels of structural complexity

The distance-based linear model showed that geometrical rather than biological variables explained more variance in the structure of fish assemblage; being the length of the colony the most important explanatory variable Table 2. Our results suggest that colonies with higher complexity supported fish assemblages with higher species richness Fig. Furthermore, colonies with different morphologies also differed in the fish species composition.

Structural complexity and its implications for design of cyber-physical systems

Among damselfish, Stegastes planifroms was the most abundant species and; it was recorded in colonies with varying morphological features. And this species was also observed sharing colonies with S. However, the first was observed particularly in larger colonies, while the latter was recorded regardless of the morphological features exhibited by the shared colonies. Stegastes leucostictus was the least abundant species and was observed mostly in colonies that were not inhabited by any other of the observed damselfish species Figs.

Again, length, convex hull volume, number of peripheral branches and average number of branches were significantly correlated with both total number of species and abundance of fishes. Thus our results suggest that structural complexity measured as a multivariate property of each coral colony may affect the structure of fish assemblage, not only in terms of species richness but also in terms of total abundance. In addition, the complexity of Acropora cervicornis seemed to enable the coexistence for only some damselfish species e. Our results indicate that geometrical and biological characteristics of Acropora cervicornis may have a striking effect on the associated fish assemblage.

Results from the present study also suggest that 3D models built from videos in the field allow the quantitative estimation of geometry, size and structural complexity of a highly structurally complex coral species such as Acropora cervicornis. This suggests that the method could also be used for coral species with lower structural complexity. Nevertheless, it remains to be tested whether this method can be used in larger scales such as reef zones, reef sites or entire reef systems.

Three-dimensional reconstructions for assessing the relationship between fish assemblages and their habitat might be limited by the geomorphological characteristics of the habitat in terms of resolution Hedley et al. The difficulty associated with measuring multiple proxies of structural complexity in situ , particularly for reef-seascape studies Hedley et al.

Structural complexity (applied mathematics)

However, three-dimensional reconstruction using videos and photographs may solve this problem, especially for studies focused on small spatial scales, for it is non-invasive and retrieves multiple proxies of structural complexity. Nevertheless, the use of 3D reconstructions for establishing the correlation between fish communities and their habitats for larger spatial scales might not be as straightforward as in our study. This is because interactions and behavior between fishes and their habitats may differ from colony to reef scales Nash et al.

For example, juvenile and small fishes recorded in this study e.

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At small spatial scales e. These fishes tend to be more territorial with a restricted ability to move across reef sections compared to adult fishes, due to predation avoidance Werner et al. Therefore, juveniles and small fishes utilizing discrete colonies of A. This is the case for A. This coral species forms monospecific patches of different sizes, providing refuge from predation through the growth of their branches, which contribute to the formation of intricate structures. It is thus expected that structural characteristics of A.

Although the importance of species-specific traits of foundation species as modulators of the spatial distribution, composition and persistence of their associated community have been recognized Angelini et al. The ecological importance and threatened status of A. The results of this study provide valuable information that can be taken into account when transplanting corals fragment, as they provide evidence on key structural features related with the function of this coral as a foundation species. The size of the new patches but also the number of branches and the vertical structure of the colony are variables that should be important to consider in both, ex situ and in situ restoration programs.

Acropora cervicornis structures, full of crevices and holes, serve as refuge for different fish species, some of them being in juvenile phases. A heterogeneous habitat such as this, may facilitate coexistence between competitors within the same colony by increasing the number of available microhabitats and territories in a spatial scale ranging from centimeters to a few meters. This is particularly important for small territorial species such as damselfishes. In our site, Pomacentrids e. Considering this, it might be possible that colony complexity favors the abundance and richness of associated fish species.

This might explain why, with the exception of pomacentrid, all observed fishes were in juvenile phases. This finding further illustrates and supports that the morphology of Acropora cervicornis plays a central role in determining the abundance and species richness of their associated fish assemblages but also in determining species composition. This have been suggested for many other foundation species in both terrestrial and marine ecosystems Angelini et al.

For instance; Stegastes planifroms was observed sharing the same colonies as S. Our results suggest that coexistence between these two species is only possible if coral colonies are large and complex. This may be explained as large colonies could release competition pressure by providing enough territory for coexistence. According to Robertson , S.

Structural Complexity Management | SpringerLink

Our results suggest that S. However, S. Facilitation can expand species realized niche trough providing refuge that limits predation Bulleri et al. Acropora cervicornis could be acting as an indirect facilitator, providing physical structure that allows numerous species of fish to hide from predators and that probably would not inhabit in the same abundance in bare sand patches. Also, larger and more complex colonies have a lot of branches that increase the available surface for territorial damselfish to establish farming territories. Most of the fish species observed in association with these colonies i.

However, live coral cover must be an important component of the habitat for it helps to maintain the structural integrity of the colonies. Even though coral cover is an important variable to estimate degradation on coral reefs Hughes, ; Bellwood et al. Nevertheless, the majority of these studies are not directly comparable with our findings for they were conducted in the Pacific, a bioregion with larger number of coral and fish species and where many fish species have being reported to be highly specialist Wilson et al.

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From our results, we conclude that three-dimensional reconstructions represent a valuable tool to measure variables that describe the geometry and the structural complexity of fish habitats, at least at the colony scale. This method allowed the reconstruction of colonies of Acropora cervicornis , a coral species with a complex body plan without harming the coral.

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This suggests that this procedure should also be applicable for benthic organisms with less structural complexity. It is also a low cost technique that requires little time in the field. The methodology employed in this study allowed the quantification of fish-habitat relationships using a multivariate approach. These results indicate that at least four structural variables length, convex hull volume, number of peripheral branches and average number of branches are specie-specific traits of Acropora cervicornis as a foundation species that might have an effect in the composition and spatial distribution of the associated fish assemblages.

We suggest that using multivariate instead univariate approaches to describe fish-habitat correlations, particularly for studies conducted at small spatial scales could be a more comprehensible approach to understand the nature of these relationships. Raw data containing the abundance of fishes and the geometrical characteristics of the A. Common use cases Typos, corrections needed, missing information, abuse, etc.

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