Role extraction for digraphs via neighborhood pattern similarity.

We analyze the recovery of different roles in a network modeled by a directed graph, based on the so-called Neighborhood Pattern Similarity approach. Our analysis uses results from random matrix theory to show that, when assuming that the graph is generated as a particular stochastic block model with Bernoulli probability distributions for the different blocks, then the recovery is asymptotically correct when the graph has a sufficiently large dimension. Under these assumptions there is a sufficient gap between the dominant and dominated eigenvalues of the similarity matrix, which guarantees the asymptotic correct identification of the number of different roles.

Computation of the Analytic Center of the Solution Set of the Linear Matrix Inequality Arising in Continuous- and Discrete-Time Passivity Analysis.

In this paper formulas are derived for the analytic center of the solution set of linear matrix inequalities (LMIs) defining passive transfer functions. The algebraic Riccati equations that are usually associated with such systems are related to boundary points of the convex set defined by the solution set of the LMI. It is shown that the analytic center is described by closely related matrix equations, and their properties are analyzed for continuous- and discrete-time systems.

TreeScaper: Visualizing and Extracting Phylogenetic Signal from Sets of Trees.

Modern phylogenomic analyses often result in large collections of phylogenetic trees representing uncertainty in individual gene trees, variation across genes, or both. Extracting phylogenetic signal from these tree sets can be challenging, as they are difficult to visualize, explore, and quantify. To overcome some of these challenges, we have developed TreeScaper, an application for tree set visualization as well as the identification of distinct phylogenetic signals.

Significant scales in community structure.

Many complex networks show signs of modular structure, uncovered by community detection. Although many methods succeed in revealing various partitions, it remains difficult to detect at what scale some partition is significant. This problem shows foremost in multi-resolution methods.

Dynamical models explaining social balance and evolution of cooperation.

Social networks with positive and negative links often split into two antagonistic factions. Examples of such a split abound: revolutionaries versus an old regime, Republicans versus Democrats, Axis versus Allies during the second world war, or the Western versus the Eastern bloc during the Cold War. Although this structure, known as social balance, is well understood, it is not clear how such factions emerge.

Narrow scope for resolution-limit-free community detection.

Detecting communities in large networks has drawn much attention over the years. While modularity remains one of the more popular methods of community detection, the so-called resolution limit remains a significant drawback. To overcome this issue, it was recently suggested that instead of comparing the network to a random null model, as is done in modularity, it should be compared to a constant factor.

Comparison of ultrasonography and physical examination in the diagnosis of incisional hernia in a prospective study.

Purpose: Incisional hernia is a frequent complication of abdominal surgery (incidence 2-20%). Diagnosis by physical examination is sometimes difficult, especially in small incisional hernias or in obese patients. The additional diagnostic value of standardized ultrasonography was evaluated in this prospective study.

Randomized clinical trial comparing polypropylene or polydioxanone for midline abdominal wall closure.

Background: Incisional hernia is a frequent complication of abdominal surgery, often requiring surgical intervention. This prospective randomized trial compared suture materials for closure of the fascia after abdominal surgery.

Methods: In 456 patients the abdominal fascia was closed with either non-absorbable (polypropylene; Prolene(®)) or absorbable (polydioxanone; PDS(®)) suture material.

The fine tuning of pain thresholds: a sophisticated double alarm system.

Two distinctive features characterize the way in which sensations including pain, are evoked by heat: (1) a thermal stimulus is always progressive; (2) a painful stimulus activates two different types of nociceptors, connected to peripheral afferent fibers with medium and slow conduction velocities, namely Adelta- and C-fibers. In the light of a recent study in the rat, our objective was to develop an experimental paradigm in humans, based on the joint analysis of the stimulus and the response of the subject, to measure the thermal thresholds and latencies of pain elicited by Adelta- and C-fibers. For comparison, the same approach was applied to the sensation of warmth elicited by thermoreceptors.

Role of second trials in cascades of information over networks.

We study the propagation of information in social networks. To do so, we focus on a cascade model where nodes are infected with probability p_{1} after their first contact with the information and with probability p_{2} at all subsequent contacts. The diffusion starts from one random node and leads to a cascade of infection.