152,954 research outputs found
A framework for epidemic spreading in multiplex networks of metapopulations
We propose a theoretical framework for the study of epidemics in structured
metapopulations, with heterogeneous agents, subjected to recurrent mobility
patterns. We propose to represent the heterogeneity in the composition of the
metapopulations as layers in a multiplex network, where nodes would correspond
to geographical areas and layers account for the mobility patterns of agents of
the same class. We analyze both the classical Susceptible-Infected-Susceptible
and the Susceptible-Infected-Removed epidemic models within this framework, and
compare macroscopic and microscopic indicators of the spreading process with
extensive Monte Carlo simulations. Our results are in excellent agreement with
the simulations. We also derive an exact expression of the epidemic threshold
on this general framework revealing a non-trivial dependence on the mobility
parameter. Finally, we use this new formalism to address the spread of diseases
in real cities, specifically in the city of Medellin, Colombia, whose
population is divided into six socio-economic classes, each one identified with
a layer in this multiplex formalism.Comment: 13 pages, 11 figure
Exploring the Impact of Socio-Technical Core-Periphery Structures in Open Source Software Development
In this paper we apply the social network concept of core-periphery structure
to the sociotechnical structure of a software development team. We propose a
socio-technical pattern that can be used to locate emerging coordination
problems in Open Source projects. With the help of our tool and method called
TESNA, we demonstrate a method to monitor the socio-technical core-periphery
movement in Open Source projects. We then study the impact of different
core-periphery movements on Open Source projects. We conclude that a steady
core-periphery shift towards the core is beneficial to the project, whereas
shifts away from the core are clearly not good. Furthermore, oscillatory shifts
towards and away from the core can be considered as an indication of the
instability of the project. Such an analysis can provide developers with a good
insight into the health of an Open Source project. Researchers can gain from
the pattern theory, and from the method we use to study the core-periphery
movements
Computational purification of individual tumor gene expression profiles leads to significant improvements in prognostic prediction.
Tumor heterogeneity is a limiting factor in cancer treatment and in the discovery of biomarkers to personalize it. We describe a computational purification tool, ISOpure, to directly address the effects of variable normal tissue contamination in clinical tumor specimens. ISOpure uses a set of tumor expression profiles and a panel of healthy tissue expression profiles to generate a purified cancer profile for each tumor sample and an estimate of the proportion of RNA originating from cancerous cells. Applying ISOpure before identifying gene signatures leads to significant improvements in the prediction of prognosis and other clinical variables in lung and prostate cancer
Analysis of close encounters with Ganymede and Callisto using a genetic n-body algorithm
In this work we describe a genetic algorithm which is used in order to study
orbits of minor bodies in the frames of close encounters. We find that the
algorithm in combination with standard orbital numerical integrators can be
used as a good proxy for finding typical orbits of minor bodies in close
encounters with planets and even their moons, saving a lot of computational
time compared to long-term orbital numerical integrations. Here, we study close
encounters of Centaurs with Callisto and Ganymede in particular. We also
perform n-body numerical simulations for comparison. We find typical impact
velocities to be between and for
Ganymede and between and for
Callisto.Comment: 18 pages, 3 figure
Desktop security as a three-dimensional problem
In this paper we argue against viewing computer desktop security solely as a technical issue. Instead, we propose a perspective that combines three related dimensions: technical infrastructure, usability and user engagement. In this light, we suggest that a viable approach to desktop security should embrace these three key dimensions of the end-user context. An example desktop application is described that has been engineered to embody these dimensions in support of the desktop user
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