Characterizing Turbulence Structure along Woody Vegetated Banks in Incised Channels: Implications for Stream Restoration

The impacts of urbanization have modified natural watersheds and stream hydraulic, hydrologic, and geomorphic processes that have lead to geomorphic and ecological disturbances in natural stream systems. These alterations have resulted in channel incision and the loss of channel-scale hydraulic characteristics responsible for initiating and maintaining pool-riffle bedforms, which are capable of supporting diverse biological stream ecosystems. Through the use of FLOW-3D, a 3-dimensional computational fluid dynamics model, three scenarios of an urban, incised, and channelized stream were simulated to characterize the turbulent, hydraulic structure during bankfull discharge. The simulations were conducted with trees inhibiting bankfull flow (representing the channel’s current state), trees removed from the channel, and a restoration design using three clusters of the original trees to initiate flow acceleration-deceleration regions. These simulations suggested that hydraulic processes found to initiate and maintain pool-riffle sequences can be restored to impaired urbanized channels for which these processes have been lost. This research can be applied to stream restoration design in hopes to establish less invasive procedures that can promote the development and maintenance of natural stream processes. If the natural processes can be restored to the channel, it is likely the project will have a higher degree of success in the future of the stream system

Multi-concentric optimal charging cordon design

The performance of a road pricing scheme varies greatly by its actual design and implementation. The design of the scheme is also normally constrained by several practicality requirements. One of the practicality requirements which is tackled in this paper is the topology of the charging scheme. The cordon shape of the pricing scheme is preferred due to its user-friendliness (i.e. the scheme can be understood easily). This has been the design concept for several real world cases (e.g. the schemes in London, Singapore, and Norway). The paper develops a methodology for defining an optimal location of a multi-concentric charging cordons scheme using Genetic Algorithm (GA). The branch-tree structure is developed to represent a valid charging cordon scheme which can be coded using two strings of node numbers and number of descend nodes. This branch-tree structure for a single cordon is then extended to the case with multi-concentric charging cordons. GA is then used to evolve the design of a multi-concentric charging cordons scheme encapsulated in the twostring chromosome. The algorithm developed, called GA-AS, is then tested with the network of the Edinburgh city in UK. The results suggest substantial improvements of the benefit from the optimised charging cordon schemes as compared to the judgemental ones which illustrate the potential of this algorithm

Evaluating strategies of phylogenetic analyses by the coherence of their results

I propose an approach to identify, among several strategies of phylogenetic analysis, those producing the most accurate results. This approach is based on the hypothesis that the more a result is reproduced from independent data, the more it reflects the historical signal common to the analysed data. Under this hypothesis, the capacity of an analytical strategy to extract historical signal should correlate positively with the coherence of the obtained results. I apply this approach to a series of analyses on empirical data, basing the coherence measure on the Robinson-Foulds distances between the obtained trees. At first approximation, the analytical strategies most suitable for the data produce the most coherent results. However, risks of false positives and false negatives are identified, which are difficult to rule out.Comment: 6 pages, 3 figures, accepted for publication in Comptes Rendus Palevol, based on a work presented at the "Journ\'ees d'automne 2012 de la Soci\'et\'e Fran\c{c}aise de Syst\'ematique" (http://www.normalesup.org/~bli/Papers/SFS_2012_BL.pdf

Measuring constructive alignment: an alignment metric to guide good practice

We present a computational model that represents and computes the level to which an educational design is constructively aligned. The model is able to provide ‘alignment metrics’ for both holistic and individual aspects of a programme or module design. A systemic and structural perspective of teaching and learning underpins the design of the computational model whereby Bloom’s taxonomy is used as a basis for categorising the core components of a teaching system and some basic principles of generative linguistics are borrowed for representing alignment structures and relationships. The degree of alignment is computed using Set theory and linear algebra. The model presented forms the main processing framework of a software tool currently being developed to facilitate teachers to systematically and consistently produce constructively aligned programmes of teaching and learning. It is envisaged that the model will have broad appeal as it allows the quality of educational designs to be measured and works on the principle of ‘practice techniques’ and ‘learning elicited’ as opposed to content

Eilenberg swindles and higher large scale homology of products of trees

We show that uniformly finite homology of products of $n$ trees vanishes in all degrees except degree $n$, where it is infinite dimensional. Our method is geometric and applies to several large scale homology theories, including almost equivariant homology and controlled coarse homology. As an application we determine group homology with $\ell_{\infty}$-coefficients of lattices in products of trees. We also show a characterization of amenability in terms of 1-homology and construct aperiodic tilings using higher homology.Comment: Final version, to appear in Groups, Geometry & Dynamic

Evolutionary and Ecological Trees and Networks

Evolutionary relationships between species are usually represented in phylogenies, i.e. evolutionary trees, which are a type of networks. The terminal nodes of these trees represent species, which are made of individuals and populations among which gene flow occurs. This flow can also be represented as a network. In this paper we briefly show some properties of these complex networks of evolutionary and ecological relationships. First, we characterize large scale evolutionary relationships in the Tree of Life by a degree distribution. Second, we represent genetic relationships between individuals of a Mediterranean marine plant, Posidonia oceanica, in terms of a Minimum Spanning Tree. Finally, relationships among plant shoots inside populations are represented as networks of genetic similarity.Comment: 6 pages, 5 figures. To appear in Proceedings of the Medyfinol06 Conferenc