Deaf, Dumb, and Chatting Robots, Enabling Distributed Computation and Fault-Tolerance Among Stigmergic Robot

We investigate ways for the exchange of information (explicit communication) among deaf and dumb mobile robots scattered in the plane. We introduce the use of movement-signals (analogously to flight signals and bees waggle) as a mean to transfer messages, enabling the use of distributed algorithms among the robots. We propose one-to-one deterministic movement protocols that implement explicit communication. We first present protocols for synchronous robots. We begin with a very simple coding protocol for two robots. Based on on this protocol, we provide one-to-one communication for any system of n \geq 2 robots equipped with observable IDs that agree on a common direction (sense of direction). We then propose two solutions enabling one-to-one communication among anonymous robots. Since the robots are devoid of observable IDs, both protocols build recognition mechanisms using the (weak) capabilities offered to the robots. The first protocol assumes that the robots agree on a common direction and a common handedness (chirality), while the second protocol assumes chirality only. Next, we show how the movements of robots can provide implicit acknowledgments in asynchronous systems. We use this result to design asynchronous one-to-one communication with two robots only. Finally, we combine this solution with the schemes developed in synchronous settings to fit the general case of asynchronous one-to-one communication among any number of robots. Our protocols enable the use of distributing algorithms based on message exchanges among swarms of Stigmergic robots. Furthermore, they provides robots equipped with means of communication to overcome faults of their communication device

Differences in outcomes over time with exclusive enteral nutrition compared to steroids in children with mild to moderate Crohn's Disease: results from the GROWTH CD study

Background: Exclusive enteral nutrition (EEN) and corticosteroids (CS) both induce similar rates of remission in mild to moderate pediatric Crohn's disease (CD), but differ with regard to mucosal healing. Our goal was to evaluate if EEN at diagnosis was superior to CS for improving long term outcomes. Methods: We prospectively followed newly diagnosed children <17 years with mild to moderate disease at baseline for two years in the GROWTH CD study. Patients were evaluated at baseline and at 8, 12, 78, and 104 weeks. Remission, relapses, complications (fibrostenotic, penetrating disease, and active perianal disease) and growth were recorded throughout the study. A propensity score analysis was performed. Results: 147 children (mean age 12.9+/-3.2 years), treated by EEN (n=60) or CS (n=87) were included. New complications developed in 13.7% of CS (12/87) versus 11.6% of EEN (7/60), p=0.29. Remission was achieved in 41/87 (47%) in CS and 38/60 (63%) EEN, p=0.036. Median time to relapse did not differ (14.4+/-1 months with CS, 16.05+/-1.1 EEN, p=0.28). Mean height Z scores decreased from week 0 to week 78 with CS (-0.34+/-1.1 to -0.51+/-1.2, p=0.01), but not with EEN (-0.32+/- 1.1 to -0.22+/- 0.9 p=0.56). In a propensity score analysis, EEN was superior to CS for inducing remission (p=0.05) and trended to superiority for height Z score (p=0.055). Conclusions: Use of EEN was associated with higher remission rates and a trend toward better growth but similar relapse and complication rates in new onset mild to moderate paediatric CD

Search in Complex Networks : a New Method of Naming

We suggest a method for routing when the source does not posses full information about the shortest path to the destination. The method is particularly useful for scale-free networks, and exploits its unique characteristics. By assigning new (short) names to nodes (aka labelling) we are able to reduce significantly the memory requirement at the routers, yet we succeed in routing with high probability through paths very close in distance to the shortest ones.Comment: 5 pages, 4 figure

Social Media and Depressive Symptoms in Childhood and Adolescence: A Systematic Review

Concerns are increasingly raised in academic and lay literature about the impact of the internet on young people’s well-being. This systematic review examined empirical research on the relationship between social media use and depressive symptoms in the child and adolescent population. A systematic search of Medline, PsycInfo and Embase databases yielded eleven eligible studies. Relevant results were extracted from each study, with a total sample of 12,646. Analysis revealed a small but statistically significant correlation between social media use and depressive symptoms in young people. However, studies varied widely in methods, sample size and results, making the clinical significance of these findings nuanced. Over half of the studies were cross-sectional, while those of longitudinal design were of limited duration. This review justifies further investigation of this phenomenon, with a need for consensus on variables and measurement

Deaf, Dumb, and Chatting Asynchronous Robots

International audienceNo abstract

Self-stabilization and Byzantine Tolerance for Maximal Matching

International audienc

Cryptographic Verification by Typing for a Sample Protocol Implementation

International audienceType systems are effective tools for verifying the security of cryptographic protocols and implementations. They provide automation, modularity and scalability, and have been applied to large protocols. In this tutorial, we illustrate the use of types for verifying authenticity properties, first using a symbolic model of cryptography, then relying on a concrete computational assumption.(1) We introduce refinement types (that is, types carrying formulas to record invariants) for programs written in F# and verified by F7, an SMT-based type checker.(2) We describe a sample authenticated RPC protocol, we implement it in F#, and we specify its security against active adversaries.(3) We develop a sample symbolic library, we present its main cryptographic invariants, and we show that our RPC implementation is perfectly secure when linked to this symbolic library.(4) We implement the same library using concrete cryptographic primitives, we make a standard computational assumption, and we show that our RPC implementation is also secure with overwhelming probability when linked to this concrete library

Complicated Disease and Response to Initial Therapy Predicts Early Surgery in Paediatric Crohn's Disease: Results From the Porto Group GROWTH Study

Introduction: The ability to predict risk for poor outcomes in Crohn's disease [CD] would enable early treatment intensification. We aimed to identify children with CD with complications at baseline and throughout the study period who are at risk for surgery 2 years from diagnosis. Methods: Newly diagnosed children with CD were enrolled into a prospective, multicentre inception cohort. Disease characteristics and serological markers were obtained at baseline and week 12 thereafter. Outcome data including disease activity, therapies, complications and need for surgery were collected until the end of 104 weeks. A chi-square automatic interaction detection [CHAID] algorithm was used to develop a prediction model for early surgery. Results: Of 285 children enrolled, 31 [10.9%] required surgery within 2 years. Multivariate analysis identified stricturing disease at baseline (odds ratio [OR] 5.26, 95% confidence interval [CI] 2.02-13.67 [p = 0.001]), and Paediatric Crohn's Disease Activity Index [PCDAI] >10 at week 12 (OR 1.06, 95% CI 1.02-1.10 [p = 0.005]) as key predictors for early surgery. CHAID demonstrated that absence of strictures at diagnosis [7.6%], corticosteroid-free remission at week 12 [4.1%] and early immunomodulator therapy [0.8%] were associated with the lowest risk of surgery, while stricturing disease at diagnosis [27.1%, p < 0.001] or elevated PCDAI at week 12 [16.7%, p = 0.014] had an increased risk of surgery at follow-up. Anti-OmpC status further stratified high-risk patients. Discussion: A risk algorithm using clinical and serological variables at diagnosis and week 12 can categorize patients into high- and low-risk groups from diagnosis

Fault-Tolerant Mobile Robots

International audienceThis chapter surveys crash tolerance, self-stabilization, Byzantine fault-tolereance, and resilience to inaccuracies for the main building blocks in mobile robots networks: gathering, convergence, scattering, leader election, and flocking