423 research outputs found
Static Safety for an Actor Dedicated Process Calculus by Abstract Interpretation
The actor model eases the definition of concurrent programs with non uniform
behaviors. Static analysis of such a model was previously done in a data-flow
oriented way, with type systems. This approach was based on constraint set
resolution and was not able to deal with precise properties for communications
of behaviors. We present here a new approach, control-flow oriented, based on
the abstract interpretation framework, able to deal with communication of
behaviors. Within our new analyses, we are able to verify most of the previous
properties we observed as well as new ones, principally based on occurrence
counting
Orchestrating Tuple-based Languages
The World Wide Web can be thought of as a global computing architecture supporting the deployment of distributed networked applications. Currently, such applications can be programmed by resorting mainly to two distinct paradigms: one devised for orchestrating distributed services, and the other designed for coordinating distributed (possibly mobile) agents. In this paper, the issue of designing a pro-
gramming language aiming at reconciling orchestration and coordination is investigated. Taking as starting point the orchestration calculus Orc and the tuple-based coordination language Klaim, a new formalism is introduced combining concepts and primitives of the original calculi.
To demonstrate feasibility and effectiveness of the proposed approach, a prototype implementation of the new formalism is described and it is then used to tackle a case study dealing with a simplified but realistic electronic marketplace, where a number of on-line stores allow client
applications to access information about their goods and to place orders
Effects of Contact Network Models on Stochastic Epidemic Simulations
The importance of modeling the spread of epidemics through a population has
led to the development of mathematical models for infectious disease
propagation. A number of empirical studies have collected and analyzed data on
contacts between individuals using a variety of sensors. Typically one uses
such data to fit a probabilistic model of network contacts over which a disease
may propagate. In this paper, we investigate the effects of different contact
network models with varying levels of complexity on the outcomes of simulated
epidemics using a stochastic Susceptible-Infectious-Recovered (SIR) model. We
evaluate these network models on six datasets of contacts between people in a
variety of settings. Our results demonstrate that the choice of network model
can have a significant effect on how closely the outcomes of an epidemic
simulation on a simulated network match the outcomes on the actual network
constructed from the sensor data. In particular, preserving degrees of nodes
appears to be much more important than preserving cluster structure for
accurate epidemic simulations.Comment: To appear at International Conference on Social Informatics (SocInfo)
201
Robust modeling of human contact networks across different scales and proximity-sensing techniques
The problem of mapping human close-range proximity networks has been tackled
using a variety of technical approaches. Wearable electronic devices, in
particular, have proven to be particularly successful in a variety of settings
relevant for research in social science, complex networks and infectious
diseases dynamics. Each device and technology used for proximity sensing (e.g.,
RFIDs, Bluetooth, low-power radio or infrared communication, etc.) comes with
specific biases on the close-range relations it records. Hence it is important
to assess which statistical features of the empirical proximity networks are
robust across different measurement techniques, and which modeling frameworks
generalize well across empirical data. Here we compare time-resolved proximity
networks recorded in different experimental settings and show that some
important statistical features are robust across all settings considered. The
observed universality calls for a simplified modeling approach. We show that
one such simple model is indeed able to reproduce the main statistical
distributions characterizing the empirical temporal networks
Ecological Assessment of Everyday Executive Functioning at Home and at School using the BRIEF Questionnaire following Childhood Traumatic Brain Injury (TBI)
IntroductionCognitive and behavioural aspects of executive functioning (EF) are frequently impaired following childhood TBI. The Behavior Rating Inventory of Executive Function (BRIEF) questionnaire provides an ecological assessment of EFs in everyday life in home and school environments. The aims of this study were to describe the dysexecutive disorders in children with TBI using the BRIEF; to compare parent- and teacher-ratings and to analyse the demographic and medical variables influencing outcome.MethodsParticipants: Children/adolescents aged 5–17 years 11 months, referred to a paediatric rehabilitation department following TBI. Outcome measures: the parent–and the teacher-report of the BRIEF were collected during neuropsychological assessment (2009–2014), as well as the teacher-report (from 2014). Age at injury and assessment, parental education and TBI severity were collected.Results194 patients (142 boys) participated in the study [mild (n=13), moderate (n=12) or severe (n=169: mean duration of coma 7.2 days; SD=6.5)]. 193 parent-reports and 28 complete teacher reports of the BRIEF were available. Mean age at injury/assessment were 6.9 (SD=4.4), and 11.8 (SD=3.5) years respectively. According to parent-ratings, children had significantly elevated scores in all BRIEF indices [Global Executive Composite (GEC), Behaviour Regulation Index (BRI), Metacognition Index (MI)], and subscales (mean T-scores 61–64; all P<.0001), with 24% to 48.0% scoring in the clinical range. Teachers’ ratings indicated similar deficits in all sub-scales (mean T-scores 63–70; all P<.001), with 39.3–57.2% scoring in the clinical range. For patients with teacher and parent-reports (n=27), no significant difference was found between parent and teacher ratings, which were significantly correlated (r: .44–.72). Regression analyses indicated that GEC was significantly predicted by older age at assessment. The regression model for BRI was not significant. For MI, younger age at injury and older age at assessment were significant predictors.Discussion and conclusionThis study highlights elevated levels of executive dysfunction in everyday life following childhood TBI, evident in home and school environments. Younger age at injury seems to influence the cognitive rather than the behavioural aspects of EFs, whereas older age at assessment is related to higher levels of complaints, probably due to the increasing levels of expectations
Expressive Synchronization Types for Inheritance in the Join Calculus
In prior work, Fournet et al. proposed an extension of the join calculus with class-based inheritance, aiming to provide a precise semantics for concurrent objects. However, as we show here, their system suffers from several limitations, which make it inadequate to form the basis of a practical implementation. In this paper, we redesign the static semantics for inheritance in the join calculus, equipping class types with more precise information. Compared to previous work, the new type system is more powerful, more expressive and simpler. Additionally, one runtime check of the old system is suppressed in the new design. We also prove the soundness of the new system, and have implemented type inference
Implementing Joins using Extensible Pattern Matching
Join patterns are an attractive declarative way to synchronize both threads and asynchronous distributed computations. We explore joins in the context of extensible pattern matching that recently appeared in languages such as F# and Scala. Our implementation supports join patterns with multiple synchronous events, and guards. Furthermore, we integrated joins into an existing actor-based concurrency framework. It enables join patterns to be used in the context of more advanced synchronization modes, such as future-type message sending and token-passing continuations
Biochemical Reaction Rules with Constraints
International audienceWe propose React(C), an expressive programming language for stochastic modeling and simulation in systems biology, that is based on biochemical reactions with constraints. We prove that React(C) can express the stochastic pi-calculus, in contrast to previous rule-based programming languages, and further illustrate the high expressiveness of React(C). We present a stochastic simulator for React(C) independently of the choice of the constraint language C. Our simulator must decide for a given reaction rule whether it can be applied to the current biochemical solution. We show that this decision problem is NP-complete for arbitrary constraint systems C, and that it can be solved in polynomial time for rules of bounded arity. In practice, we propose to solve this problem by constraint programming
Exploring concurrency and reachability in the presence of high temporal resolution
Network properties govern the rate and extent of spreading processes on
networks, from simple contagions to complex cascades. Recent advances have
extended the study of spreading processes from static networks to temporal
networks, where nodes and links appear and disappear. We review previous
studies on the effects of temporal connectivity for understanding the spreading
rate and outbreak size of model infection processes. We focus on the effects of
"accessibility", whether there is a temporally consistent path from one node to
another, and "reachability", the density of the corresponding "accessibility
graph" representation of the temporal network. We study reachability in terms
of the overall level of temporal concurrency between edges, quantifying the
overlap of edges in time. We explore the role of temporal resolution of
contacts by calculating reachability with the full temporal information as well
as with a simplified interval representation approximation that demands less
computation. We demonstrate the extent to which the computed reachability
changes due to this simplified interval representation.Comment: To appear in Holme and Saramaki (Editors). "Temporal Network Theory".
Springer- Nature, New York. 201
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