21 research outputs found
The global migration network of sex-workers
Differences in the social and economic environment across countries encourage
humans to migrate in search of better living conditions, including job
opportunities, higher salaries, security and welfare. Quantifying global
migration is, however, challenging because of poor recording, privacy issues
and residence status. This is particularly critical for some classes of
migrants involved in stigmatised, unregulated or illegal activities. Escorting
services or high-end prostitution are well-paid activities that attract workers
all around the world. In this paper, we study international migration patterns
of sex-workers by using network methods. Using an extensive international
online advertisement directory of escorting services and information about
individual escorts, we reconstruct a migrant flow network where nodes represent
either origin or destination countries. The links represent the direct routes
between two countries. The migration network of sex-workers shows different
structural patterns than the migration of the general population. The network
contains a strong core where mutual migration is often observed between a group
of high-income European countries, yet Europe is split into different network
communities with specific ties to non-European countries. We find
non-reciprocal relations between countries, with some of them mostly offering
while others attract workers. The GDP per capita is a good indicator of country
attractiveness for incoming workers and service rates but is unrelated to the
probability of emigration. The median financial gain of migrating, in
comparison to working at the home country, is 15.9%. Only sex-workers coming
from 77% of the countries have financial gains with migration and average gains
decrease with the GDPc of the country of origin. Our results shows that
high-end sex-worker migration is regulated by economic, geographic and cultural
aspects.Comment: Comments and feedback welcomed. Two tables and 6 figures including S
TDANetVis: Suggesting temporal resolutions for graph visualization using zigzag persistent homology
Temporal graphs are commonly used to represent complex systems and track the
evolution of their constituents over time. Visualizing these graphs is crucial
as it allows one to quickly identify anomalies, trends, patterns, and other
properties leading to better decision-making. In this context, the
to-be-adopted temporal resolution is crucial in constructing and analyzing the
layout visually. The choice of a resolution is critical, e.g., when dealing
with temporally sparse graphs. In such cases, changing the temporal resolution
by grouping events (i.e., edges) from consecutive timestamps, a technique known
as timeslicing, can aid in the analysis and reveal patterns that might not be
discernible otherwise. However, choosing a suitable temporal resolution is not
trivial. In this paper, we propose TDANetVis, a methodology that suggests
temporal resolutions potentially relevant for analyzing a given graph, i.e.,
resolutions that lead to substantial topological changes in the graph
structure. To achieve this goal, TDANetVis leverages zigzag persistent
homology, a well-established technique from Topological Data Analysis (TDA). To
enhance visual graph analysis, TDANetVis also incorporates the colored barcode,
a novel timeline-based visualization built on the persistence barcodes commonly
used in TDA. We demonstrate the usefulness and effectiveness of TDANetVis
through a usage scenario and a user study involving 27 participants.Comment: This document contains the main article and supplementary material.
For associated code and software, see
https://github.com/raphaeltinarrage/TDANetVi
DyNetVis: a system for visualization of dynamic networks
The concept of networks has been important in the study of complex systems. In networks, links connect pairs of nodes forming complex structures. Studies have shown that networks not only contain structure but may also evolve in time. The addition of the temporal dimension adds complexity on the analysis and requests the development of innovative methods for the visualization of real-life networks. In this paper we introduce the Dynamic Network Visualization System (DyNetVis), a software tool for visualization of dynamic networks. The system provides several tools for user interaction and offers two coordinated visual layouts, named structural and temporal. Structural refers to standard network drawing techniques, in which a single snapshot of nodes and links are placed in a plane, whereas the temporal layout allows for simultaneously visualization of several temporal snapshots of the dynamic network. In addition, we also investigate two approaches for temporal layout visualization: (i) Recurrent Neighbors, a node ordering strategy that highlights frequent connections in time, and (ii) Temporal Activity Map (TAM), a layout technique with focus on nodes activity. We illustrate the applicability of the layouts and interaction functionalities provided by the system in two visual analysis case studies, demonstrating their advantages to improve the overall user experience on visualization and exploratory data analysis on dynamic networks
Perturbing Topological Field Theories
The abelian Chern-Simons theory is perturbed by introducing local
gauge-invariant interaction terms depending on the curvature. The computation
of the correlation function of two Wilson lines for two smooth closed
nonintersecting curves is reported up to four loops and is shown to be
unaffected by radiative corrections. This result ensures the stability of the
linking number of the two curves with respect to the local perturbations which
may be added to the Chern-Simons action.Comment: 13 pages, 5 figures, corrected some typo
The global migration network of sex-workers
Differences in the social and economic environment across countries encourage humans to migrate in search of better living conditions, including job opportunities, higher salaries, security and welfare. Quantifying global migration is, however, challenging because of poor recording, privacy issues and residence status. This is particularly critical for some classes of migrants involved in stigmatised, unregulated or illegal activities. Escorting services or high-end prostitution are well-paid activities that attract workers all around the world. In this paper, we study international migration patterns of sex-workers by using network methods. Using an extensive international online advertisement directory of escorting services and information about individual escorts, we reconstruct a migrant flow network where nodes represent either origin or destination countries. The links represent the direct routes between two countries. The migration network of sex-workers shows different structural patterns than the migration of the general population. The network contains a strong core where mutual migration is often observed between a group of high-income European countries, yet Europe is split into different network communities with specific ties to non-European countries. We find non-reciprocal relations between countries, with some of them mostly offering while others attract workers. The Gross Domestic Product per capita (GDPc) is a good indicator of country attractiveness for incoming workers and service rates but is unrelated to the probability of emigration. The median financial gain of migrating, in comparison to working at the home country, is 15.9%. Only sex-workers coming from 77% of the countries have financial gains with migration and average gains decrease with the GDPc of the country of origin. Our results suggest that high-end sex-worker migration is regulated by economic, geographic and cultural aspects
A streaming edge sampling method for network visualization
Visualization strategies facilitate streaming network analysis by allowing its exploration through graphical and interactive layouts. Depending on the strategy and the network density, such layouts may suffer from a high level of visual clutter that hides meaningful temporal patterns, highly active groups of nodes, bursts of activity, and other important network properties. Edge sampling improves layout readability, highlighting important properties and leading to easier and faster pattern identification and decision making. This paper presents Streaming Edge Sampling for Network Visualization-SEVis, a streaming edge sampling method that discards edges of low-active nodes while preserving a distribution of edge counts that is similar to the original network. It can be applied to a variety of layouts to enhance streaming network analyses. We evaluated SEVis performance using synthetic and real-world networks through quantitative and visual analyses. The results indicate a higher performance of SEVis for clutter reduction and pattern identification when compared with other sampling methods
DyNetVis : an interactive software to visualize structure and epidemics on temporal networks
The study of complex networks, especially temporal networks, increased over the last years. Understanding patterns, trends, and anomalies in these networks, as well as simulating and analyzing dynamic processes (e.g., infection spread dynamics in social networks), are not trivial tasks. Information Visualization techniques offer significant potential to assist the user in these analyses. This paper presents an extended version of Dynamic Network Visualization (DyNetVis), a freely available and open-source interactive software to perform visual analysis of temporal networks. It provides four visualization techniques, structural, temporal, matrix, and community layouts, and a number of state-of-the-art methods to interact with each of these layouts. DyNetVis also implements dynamic processes, including standard epidemic models. It is a computational tool to study and explore networks in diverse domains
Perturbing Topological Field Theories
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