240,799 research outputs found
Dynamic simulation of regulatory networks using SQUAD
BACKGROUND: The ambition of most molecular biologists is the understanding of the intricate network of molecular interactions that control biological systems. As scientists uncover the components and the connectivity of these networks, it becomes possible to study their dynamical behavior as a whole and discover what is the specific role of each of their components. Since the behavior of a network is by no means intuitive, it becomes necessary to use computational models to understand its behavior and to be able to make predictions about it. Unfortunately, most current computational models describe small networks due to the scarcity of kinetic data available. To overcome this problem, we previously published a methodology to convert a signaling network into a dynamical system, even in the total absence of kinetic information. In this paper we present a software implementation of such methodology.
RESULTS: We developed SQUAD, a software for the dynamic simulation of signaling networks using the standardized qualitative dynamical systems approach. SQUAD converts the network into a discrete dynamical system, and it uses a binary decision diagram algorithm to identify all the steady states of the system. Then, the software creates a continuous dynamical system and localizes its steady states which are located near the steady states of the discrete system. The software permits to make simulations on the continuous system, allowing for the modification of several parameters. Importantly, SQUAD includes a framework for perturbing networks in a manner similar to what is performed in experimental laboratory protocols, for example by activating receptors or knocking out molecular components. Using this software we have been able to successfully reproduce the behavior of the regulatory network implicated in T-helper cell differentiation.
CONCLUSION: The simulation of regulatory networks aims at predicting the behavior of a whole system when subject to stimuli, such as drugs, or determine the role of specific components within the network. The predictions can then be used to interpret and/or drive laboratory experiments. SQUAD provides a user-friendly graphical interface, accessible to both computational and experimental biologists for the fast qualitative simulation of large regulatory networks for which kinetic data is not necessarily available
M\'ethodologie de mod\'elisation et d'impl\'ementation d'adaptateurs spatio-temporels
The re-use of pre-designed blocks is a well-known concept of the software
development. This technique has been applied to System-on-Chip (SoC) design
whose complexity and heterogeneity are growing. The re-use is made thanks to
high level components, called virtual components (IP), available in more or
less flexible forms. These components are dedicated blocks: digital signal
processing (DCT, FFT), telecommunications (Viterbi, TurboCodes),... These
blocks rest on a model of fixed architecture with very few degrees of
personalization. This rigidity is particularly true for the communication
interface whose orders of acquisition and production of data, the temporal
behavior and protocols of exchanges are fixed. The successful integration of
such an IP requires that the designer (1) synchronizes the components (2)
converts the protocols between "incompatible" blocks (3) temporizes the data to
guarantee the temporal constraints and the order of the data. This phase
remains however very manual and source of errors. Our approach proposes a
formal modeling, based on an original Ressource Compatibility Graph. The
synthesis flow is based on a set of transformations of the initial graph to
lead to an interface architecture allowing the space-time adaptation of the
data exchanges between several components
Input-output Conformance Testing for Channel-based Service Connectors
Service-based systems are software systems composed of autonomous components or services provided
by different vendors, deployed on remote machines and accessible through the web. One of the
challenges of modern software engineering is to ensure that such a system behaves as intended by its
designer. The Reo coordination language is an extensible notation for formal modeling and execution
of service compositions. Services that have no prior knowledge about each other communicate
through advanced channel connectors which guarantee that each participant, service or client, receives
the right data at the right time. Each channel is a binary relation that imposes synchronization
and data constraints on input and output messages. Furthermore, channels are composed together
to realize arbitrarily complex behavioral protocols. During this process, a designer may introduce
errors into the connector model or the code for their execution, and thus affect the behavior of a
composed service. In this paper, we present an approach for model-based testing of coordination
protocols designed in Reo. Our approach is based on the input-output conformance (ioco) testing
theory and exploits the mapping of automata-based semantic models for Reo to equivalent process
algebra specifications
Port Protocols for Deadlock-Freedom of Component Systems
In component-based development, approaches for property verification exist
that avoid building the global system behavior of the component model.
Typically, these approaches rely on the analysis of the local behavior of fixed
sized subsystems of components. In our approach, we want to avoid not only the
analysis of the global behavior but also of the local behaviors of the
components. Instead, we consider very small parts of the local behaviors called
port protocols that suffice to verify properties.Comment: In Proceedings ICE 2010, arXiv:1010.530
Components Interoperability through Mediating Connector Patterns
A key objective for ubiquitous environments is to enable system
interoperability between system's components that are highly heterogeneous. In
particular, the challenge is to embed in the system architecture the necessary
support to cope with behavioral diversity in order to allow components to
coordinate and communicate. The continuously evolving environment further asks
for an automated and on-the-fly approach. In this paper we present the design
building blocks for the dynamic and on-the-fly interoperability between
heterogeneous components. Specifically, we describe an Architectural Pattern
called Mediating Connector, that is the key enabler for communication. In
addition, we present a set of Basic Mediator Patterns, that describe the basic
mismatches which can occur when components try to interact, and their
corresponding solutions.Comment: In Proceedings WCSI 2010, arXiv:1010.233
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