Versatility of nodal affiliation to communities

Graph theoretical analysis of the community structure of networks attempts to identify the communitites (or modules) to which each node affiliates. However, this is in most cases an ill-posed problem, as the affiliation of a node to a single community is often ambiguous. Previous solutions have attempted to identify all of the communities to which each node affiliates. Instead of taking this approach, we introduce versatility, V, as a novel metric of nodal affiliation: V = 0 means that a node is consistently assigned to a specific community; V > 0 means it is inconsistently assigned to different communities. Versatility works in conjunction with existing community detection algorithms and it satisfies many theoretically desirable properties in idealised networks designed to maximise ambiguity of modular decomposition. The local minima of global mean versatility identified the resolution parameters of a hierarchical community detection algorithm that least ambiguously decomposed the community structure of a social (karate club) network and the mouse brain connectome. Our results suggest that nodal versatility is useful in quantifying the inherent ambiguity of modular decomposition.Churchill Foundation NIH Oxford-Cambridge Scholars Foundation Gates Cambridge Trust NIHR Cambridge Biomedical Research Centr

Extinction-induced community reorganization in bipartite networks

We study how the community structure of bipartite mutualistic networks changes in a dynamic context. First, we consider a real mutualistic network and introduce extinction events according to several scenarios. We model extinctions as node or interaction removals. For node removal, we consider random, directed and sequential extinctions; for interaction removal, we consider random extinctions. The bipartite network reorganizes showing an increase of the effective modularity and a fast decrease of the persistence of the species in the original communities with increasing number of extinction events. Second, we compare extinctions in a real mutualistic network with the growth of a bipartite network model. The modularity reaches a stationary value and nodes remain in the same community after joining the network. Our results show that perturbations and disruptive events affect the connectivity pattern of mutualistic networks at the mesoscale level. The increase of the effective modularity observed in some scenarios could provide some protection to the remaining ecosystem

Using discourse analysis to understand professional music teacher identity

©2021 Anne Jordhus-Lier. This is an Open Access article distributed under the terms of the Creative Commons CC-BY 4.0 License (https://creativecommons.org/licenses/by/4.0/).The purpose of this article is to discuss the use of discourse analysis in order to understand music teachers’ professional identities. This is done by elaborating on the theory and methodology of a study on professional identities of music teachers within the Norwegian municipal school of music and performing arts. Theoretical and methodological perspectives, including research design, analysis, results, validity and ethics, are discussed in the article. An argument in favour of discourse analysis is put forward: that it offers focus on the context, complexity and power relations of the field, as well as providing an understanding of how identities are constructed and negotiated. The use of discourse analysis in the study provided analytical tools which challenged taken-for-granted knowledge, discovered binary discursive oppositions, and unmasked power relations. The study found that teachers construct their identities within a contested discursive field where meanings are attached to the work they perform, as well as to the institutions they represent.publishedVersio

Refinement type contracts for verification of scientific investigative software

Our scientific knowledge is increasingly built on software output. User code which defines data analysis pipelines and computational models is essential for research in the natural and social sciences, but little is known about how to ensure its correctness. The structure of this code and the development process used to build it limit the utility of traditional testing methodology. Formal methods for software verification have seen great success in ensuring code correctness but generally require more specialized training, development time, and funding than is available in the natural and social sciences. Here, we present a Python library which uses lightweight formal methods to provide correctness guarantees without the need for specialized knowledge or substantial time investment. Our package provides runtime verification of function entry and exit condition contracts using refinement types. It allows checking hyperproperties within contracts and offers automated test case generation to supplement online checking. We co-developed our tool with a medium-sized ($\approx$3000 LOC) software package which simulates decision-making in cognitive neuroscience. In addition to helping us locate trivial bugs earlier on in the development cycle, our tool was able to locate four bugs which may have been difficult to find using traditional testing methods. It was also able to find bugs in user code which did not contain contracts or refinement type annotations. This demonstrates how formal methods can be used to verify the correctness of scientific software which is difficult to test with mainstream approaches

AN EDGE-CENTRIC PERSPECTIVE FOR BRAIN NETWORK COMMUNITIES

Thesis (Ph.D.) - Indiana University, Department of Psychological and Brain Sciences and Program in Neuroscience, 2021The brain is a complex system organized on multiple scales and operating in both a local and distributed manner. Individual neurons and brain regions participate in specific functions, while at the same time existing in the context of a larger network, supporting a range of different functionalities. Building brain networks comprised of distinct neural elements (nodes) and their interrelationships (edges), allows us to model the brain from both local and global perspectives, and to deploy a wide array of computational network tools. A popular network analysis approach is community detection, which aims to subdivide a network’s nodes into clusters that can used to represent and evaluate network organization. Prevailing community detection approaches applied to brain networks are designed to find densely interconnected sets of nodes, leading to the notion that the brain is organized in an exclusively modular manner. Furthermore, many brain network analyses tend to focus on the nodes, evidenced by the search for modular groupings of neural elements that might serve a common function. In this thesis, we describe the application of community detection algorithms that are sensitive to alternative cluster configurations, enhancing our understanding of brain network organization. We apply a framework called the stochastic block model, which we use to uncover evidence of non-modular organization in human anatomical brain networks across the life span, and in the informatically-collated rat cerebral cortex. We also propose a framework to cluster functional brain network edges in human data, which naturally results in an overlapping organization at the level of nodes that bridges canonical functional systems. These alternative methods utilize the connection patterns of brain network edges in ways that prevailing approaches do not. Thus, we motivate an alternative outlook which focuses on the importance of information provided by the brain’s interconnections, or edges. We call this an edge-centric perspective. The edge-centric approaches developed here offer new ways to characterize distributed brain organization and contribute to a fundamental change in perspective in our thinking about the brain

Governance of marine protected areas in the least-developed countries : case studies from West Africa

ISSN 2070-7010International audienceThe need for effective governance of the marine protected areas (MPAs) in least developed countries (LDCs) is commensurate with the significant territorial stakes raised by their extensive maritime domain. Another significant challenge is the conservation of biodiversity and of ecosystems whose level of productivity is similar to that of coral reefs (e.g. in East Africa and Madagascar, the Red Sea, Maldives, Cambodia, and South Pacific islands), upwelling systems (e.g. in West Africa and Angola) and estuarine and delta ecosystems (e.g. in West and East Africa, Bangladesh and Myanmar). However, the overriding issue is to reconcile conservation and human presence as, in LDCs, human activities are tolerated in almost all MPAs covered by International Union for Conservation of Nature categories II-VI. Finally, issues related to identity claims and to the process of establishment of property and other legal entitlements on nature are gaining importance. A review of the literature on fisheries and MPAs governance showed how polysemous and vague the notion of governance was until very recently and how few or oversimplified were the analyses of MPA governance in the LDCs. However, only detailed analyses would allow the characterization of governance systems and identification of their weaknesses with the view to suggesting new governance arrangements and appropriate public policy options. Such analytical deficiencies may be explained by the lack of analytical frameworks capable of taking into account the plurality and intricacy of socio-economic organizations and institutions, the sociocultural features and the role of new mediators and "development brokers" that shape MPA governance in the LDCs. The deficiencies may also be explained by the fact that the dominating hierarchical governancesystems tend to underestimate the complexity of MPA governance systems. Therefore, it has been necessary to develop an analytical framework to study the governance of MPAs in the LDCs, drawing on four sources of inspiration: (i) the interactive fisheries governance approach; (ii) the risk governance approach; (iii) the socioanthropology of mediations and brokerage; and (iv) the governance analytical framework. The framework indicates the five issues that must be addressed in order to operationalize the concept of governance in LDC MPAs: (i) definition of the problem or the issue at stake; (ii) identification of the set of relevant governance norms; (iii) presentation of the actors involved in the governance process; (iv) highlighting the nodes around which actors' strategies converge; and (v) recalling the processes that have led to the current state of governance. This analytical framework makes it possible to characterize the governance system of each of the MPAs considered and to develop a typology of these systems. The characterization of different governance systems highlights their weaknessesand paves the way for new public policy options and, more generally, for the restructuring of governance to correct these weaknesses. However, prior to the development of the analytical framework and the characterization of governance systems, the main MPA governance principles and constraints, as well their legal context, must be clarified. The whole methodology was tested on three West African coastal and marine protected areas, which seemed to provide textbook cases illustrating the difficulties of governance in LDCs: the Banc d'Arguin National Park in Mauritania, the Saloum Delta Biosphere Reserve in Senegal, and the Bolama Bijagos Archipelago Biosphere Reserve in Guinea-Bissau. The analysis of demographic and economic constraints in these West African MPAs showed the importance of: (i) increasing population density and mobility; (ii) the intensification of resource exploitation; and (iii) and the openingof the MPA economy. The analysis of the legal and institutional contexts showed the international inspiration of the MPA objectives and conservation arrangements,and the syncretism of the legal system

The genetic organization of longitudinal subcortical volumetric change is stable throughout the lifespan.

Development and aging of the cerebral cortex show similar topographic organization and are governed by the same genes. It is unclear whether the same is true for subcortical regions, which follow fundamentally different ontogenetic and phylogenetic principles. We tested the hypothesis that genetically governed neurodevelopmental processes can be traced throughout life by assessing to which degree brain regions that develop together continue to change together through life. Analyzing over 6000 longitudinal MRIs of the brain, we used graph theory to identify five clusters of coordinated development, indexed as patterns of correlated volumetric change in brain structures. The clusters tended to follow placement along the cranial axis in embryonic brain development, suggesting continuity from prenatal stages, and correlated with cognition. Across independent longitudinal datasets, we demonstrated that developmental clusters were conserved through life. Twin-based genetic correlations revealed distinct sets of genes governing change in each cluster. Single-nucleotide polymorphisms-based analyses of 38,127 cross-sectional MRIs showed a similar pattern of genetic volume-volume correlations. In conclusion, coordination of subcortical change adheres to fundamental principles of lifespan continuity and genetic organization

2023 Summer Experience Program Abstracts

https://openworks.mdanderson.org/sumexp23/1130/thumbnail.jp

The effects of Syrian refugees on Jordan’s economy: A critical case study

This project discusses the effects of Syrian refugees on the economy of the Hashemite Kingdom of Jordan. It aims at determining whether Syrian refugees have had an effect on GDP, unemployment levels, and price indexes (inflation). It also investigates whether they have had costs and benefits on Jordan and whether the benefits have outweighed the costs. It shows that Syrian refugees have had mixed effects on GDP, unemployment, and inflation, and that they have been mainly benefit to Jordan’s economy