What do we learn from correlations of local and global network properties?

In complex networks a common task is to identify the most important or "central" nodes. There are several definitions, often called centrality measures, which often lead to different results. Here we study extensively correlations between four local and global measures namely the degree, the shortest-path-betweenness, the random-walk betweenness and the subgraph centrality on different random-network models like Erdos-Renyi, Small-World and Barabasi-Albert as well as on different real networks like metabolic pathways, social collaborations and computer networks. Correlations are quite different between the real networks and the model networks questioning whether the models really reflect all important properties of the real world

Information Horizons in Networks

We investigate and quantify the interplay between topology and ability to send specific signals in complex networks. We find that in a majority of investigated real-world networks the ability to communicate is favored by the network topology on small distances, but disfavored at larger distances. We further discuss how the ability to locate specific nodes can be improved if information associated to the overall traffic in the network is available.Comment: Submitted top PR

An Empirical Analysis of Synergies and Tradeoffs between Sustainable Development Goals

The UN Sustainable Development Goals (SDGs) represent a universal agenda that nations have committed to achieving by 2030. The challenge is substantial, with no country excelling across all SDGs. Using global UN data, we assess patterns of positive and negative correlations between indicators of SDG status and progress. For nearly 70% of SDG indicators, status is positively associated with GDP/capita. Progress on SDG indicators, however, occurs in both poorer and wealthier countries. When GDP/capita is controlled for, positive associations remain between health, environment and energy usage indicators. Economic growth is negatively associated with changes in some health and environment indicators. For SDGs targets to be achieved, major opportunities and conflicts will need to be identified, prioritized and acted upon

Quantum mass corrections for affine Toda solitons

We calculate the first quantum corrections to the masses of solitons in imaginary-coupling affine Toda theories using the semi-classical method of Dashen, Hasslacher and Neveu. The theories divide naturally into those based on the simply-laced, the twisted and the untwisted non-simply-laced algebras. We find that the classical relationships between soliton and particle masses found by Olive {\em et al.\ }persist for the first two classes, but do not appear to do so naively for the third.Comment: 39pp, .uu compressed dvifile. Revised version alters two references and includes hep-th no. on Title pag

Remarks on excited states of affine Toda solitons

The identification in affine Toda field theory of the quantum particle with the lowest breather allows us to re-interpret discrete modes of excitation of solitons as breathers bound to solitons, and thus to investigate them through the proposed soliton-breather S-matrices. There are implications for the physical spectrum and for the semiclassical soliton mass corrections.Comment: 8pp, LaTeX. Comments and one reference added; version to appear in Phys.Lett.

Accessing the most lethal product on the market : community perceptions of tobacco accessibility in NSW, Australia

Aim: This study aims to describe the perceived ease of accessing tobacco retail outlets in New South Wales (NSW), Australia, and the sociodemographic factors associated with reported higher density of tobacco retail outlets. Methods: A cross-sectional online survey was conducted with a sample of NSW adults in February 2019. The accessibility of cigarettes was assessed and a binary logistic regression model was used to examine characteristics associated with having four or more retailers within a 5-minute drive of their home. Results: A total of 3213 NSW adults completed the survey. The vast majority of participants, 89.9% (n = 2888), described cigarettes as being easily accessed from where they live. Half of the participants (50.7%) reported having four or more tobacco retail outlets within a 5-minute drive of their home. Never-smokers were significantly less likely than daily smokers to report four or more tobacco retailers within a 5-minute drive of their home, although non-smokers may be less likely to identify tobacco retailers. Females, those living in regional areas of NSW and those with a university qualification were also less likely to report having four or more tobacco retailers within a 5-minute drive of their home. Conclusion: The ease of access to tobacco retailers in NSW is incongruent with the significant health risks associated with tobacco use and highlights the need for measures to reduce the supply of tobacco, such as a fee-based tobacco licensing system

Potholes and molehills: bias in the diagnostic performance of diffusion-tensor imaging in concussion

PURPOSE: To investigate the extent of bias in a clinical study involving pothole analysis of diffusion-tensor imaging (DTI) data used to quantify white matter lesion load in diseases with a heterogeneous spatial distribution of pathologic findings, such as mild traumatic brain injury (TBI), and create a mathematical model of the bias. MATERIALS AND METHODS: Use of the same reference population to define normal findings and make comparisons with a patient group introduces bias, which potentially inflates reported diagnostic performance. In this institutional review board-approved prospective observational cohort study, DTI data were obtained in 20 patients admitted to the emergency department with mild TBI and in 16 control subjects. Potholes and molehills were defined as clusters of voxels with fractional anisotropy values more than 2 standard deviations below and above the mean of the corresponding voxels in the reference population, respectively. The number and volume of potholes and molehills in the two groups were compared by using a Mann-Whitney U test. RESULTS: Standard analysis showed significantly more potholes in mild TBI than in the control group (102.5 +/- 34.3 vs 50.6 +/- 28.9, P \u3c .001). Repeat analysis by using leave-one-out cross-validation decreased the apparent difference in potholes between groups (mild TBI group, 102.5 +/- 34.3; control group, 93.4 +/- 27.2; P = .369). It was demonstrated that even with 100 subjects, this bias can decrease the voxelwise false-positive rate by more than 30% in the control group. CONCLUSION: The pothole approach to neuroimaging data may introduce bias, which can be minimized by independent training and test groups or cross-validation methods. This bias is sufficient to call into question the previously reported diagnostic performance of DTI for mild TBI

Networks based on collisions among mobile agents

We investigate in detail a recent model of colliding mobile agents [Phys. Rev. Lett.~96, 088702], used as an alternative approach to construct evolving networks of interactions formed by the collisions governed by suitable dynamical rules. The system of mobile agents evolves towards a quasi-stationary state which is, apart small fluctuations, well characterized by the density of the system and the residence time of the agents. The residence time defines a collision rate and by varying the collision rate, the system percolates at a critical value, with the emergence of a giant cluster whose critical exponents are the ones of two-dimensional percolation. Further, the degree and clustering coefficient distributions and the average path length show that the network associated with such a system presents non-trivial features which, depending on the collision rule, enables one not only to recover the main properties of standard networks, such as exponential, random and scale-free networks, but also to obtain other topological structures. Namely, we show a specific example where the obtained structure has topological features which characterize accurately the structure and evolution of social networks in different contexts, ranging from networks of acquaintances to networks of sexual contacts.Comment: 12 pages, 17 figure

Spatial Topology and its Structural Analysis based on the Concept of Simplicial Complex

This paper introduces a model that identifies spatial relationships for a structural analysis based on the concept of simplicial complex. The spatial relationships are identified through overlapping two map layers, namely a primary layer and a contextual layer. The identified spatial relationships are represented as a simplical complex, in which simplices and vertices respectively represent two layers of objects. The model relies on the simplical complex for structural representation and analysis. To quantify structural properties of individual primary objects (or equivalently simplices), and the simplicial complex as a whole, we define a set of centrality measures by considering multidimensional chains of connectivity, i.e. the number of contextual objects shared by a pair of primary objects. With the model, the interaction and relationships with a geographic system are modeled from both local and global perspectives. The structural properties and modeling capabilities are illustrated with a simple example and a case study applied to the structural analysis of an urban system.Comment: 14 pages, 7 figures, 2 tables, submitted for publicatio