256,752 research outputs found
Cormas, une plate-forme multi-agent pour concevoir collectivement des modĂšles et interagir avec les simulations
International audienceCe document présente les nouvelles fonctionnalités de Cormas, une plate-forme de modélisation multi-agent dédiée à la gestion des ressources renouvelables. Logiciel libre, Cormas vise à concevoir facilement un SMA et analyser des scénarios. Aujourd'hui, Cormas a pris une direction novatrice orientée vers la conception collective de modÚles et la simulation interactive. Ces simulations hybrides mixent des décisions prises par les joueurs et d'autres par le modÚle. Cela permet d'interagir avec une simulation en modifiant le comportement des agents et la façon dont ils utilisent les ressources. Ainsi, il est possible d'explorer collectivement des scénarios à moyen et long terme afin de mieux comprendre comment atteindre une situation souhaitée. En retour, cela permet de réviser collectivement le modÚle conceptuel. AprÚs avoir expliqué la philosophie de la modélisation d'accompagnement, ce document présente la façon dont les fonctionnalités de Cormas sont appliquées à travers trois expériences. Abstract This paper presents the new functionalities of Cormas, a multi-agent modeling platform dedicated to the management of renewable resources. As free software, Cormas is intended to facilitate the design of ABM as well as the monitoring and analysis of simulation scenarios. Today Cormas has taken an innovative direction oriented towards the collective design of models and interactive simulation. These hybrid simulations are mixing decisions taken by stakeholders and others by the model. This allows the user to interact with a simulation by changing the behavior of agents. Thus, it is possible to collectively explore medium and long-term scenarios to better understand how a desired situation may be reached. In turn, this feed back into the collective design of the model. After having explained the philosophy of the companion modeling, this paper presents how the Cormas functionalities are put into practice through three experiments with stakeholders facing actual environmental challenges
Self-organization in Communicating Groups: the emergence of coordination, shared references and collective intelligence\ud
The present paper will sketch the basic ideas of the complexity paradigm, and then apply them to social systems, and in particular to groups of communicating individuals who together need to agree about how to tackle some problem or how to coordinate their actions. I will elaborate these concepts to provide an integrated foundation for a theory of self-organization, to be understood as a non-linear process of spontaneous coordination between actions. Such coordination will be shown to consist of the following components: alignment, division of labor, workflow and aggregation. I will then review some paradigmatic simulations and experiments that illustrate the alignment of references and communicative conventions between communicating agents. Finally, the paper will summarize the preliminary results of a series of experiments that I devised in order to observe the emergence of collective intelligence within a communicating group, and interpret these observations in terms of alignment, division of labor and workflow
Properties of quasi two-dimensional condensates in highly anisotropic traps
We theoretically investigate some of the observable properties of quasi
two-dimensional condensates. Using a variational model based on a
Gaussian-parabolic trial wavefunction we calculate chemical potential,
condensate size in time-of-flight, release energy and collective excitation
spectrum for varying trap geometries and atom numbers and find good agreement
with recent published experimental results.Comment: 7 pages, 4 figure
Active Inter-cellular Forces in Collective Cell Motility
The collective behaviour of confluent cell sheets is strongly influenced both
by polar forces, arising through cytoskeletal propulsion and by active
inter-cellular forces, which are mediated by interactions across cell-cell
junctions. We use a phase-field model to explore the interplay between these
two contributions and compare the dynamics of a cell sheet when the polarity of
the cells aligns to (i) their main axis of elongation, (ii) their velocity, and
(iii) when the polarity direction executes a persistent random walk.In all
three cases, we observe a sharp transition from a jammed state (where cell
rearrangements are strongly suppressed) to a liquid state (where the cells can
move freely relative to each other) when either the polar or the inter-cellular
forces are increased. In addition, for case (ii) only, we observe an additional
dynamical state, flocking (solid or liquid), where the majority of the cells
move in the same direction. The flocking state is seen for strong polar forces,
but is destroyed as the strength of the inter-cellular activity is increased.Comment: 15 pages,22 figure
Collective cell durotaxis emerges from long-range intercellular force transmission
The ability of cells to follow gradients of extracellular matrix stiffnessâdurotaxisâhas been implicated in development, fibrosis, and cancer. Here, we found multicellular clusters that exhibited durotaxis even if isolated constituent cells did not. This emergent mode of directed collective cell migration applied to a variety of epithelial cell types, required the action of myosin motors, and originated from supracellular transmission of contractile physical forces. To explain the observed phenomenology, we developed a generalized clutch model in which local stick-slip dynamics of cell-matrix adhesions was integrated to the tissue level through cell-cell junctions. Collective durotaxis is far more efficient than single-cell durotaxis; it thus emerges as a robust mechanism to direct cell migration during development, wound healing, and collective cancer cell invasion.Peer ReviewedPostprint (author's final draft
Innovation and research in organic farming: A multiâlevel approach to facilitate cooperation among stakeholders
A wider range of stakeholders is expected to be involved in organic research. A decisionâsupport tool is needed to define priorities and to allocate tasks among institutions. Based on research and management experience in organic research, the authors have developed a framework for experimental and research
projects. The framework is based on a multiâlevel approach. Each level is defined according to the directness of the innovation impact on the organic systems. The projects carried out for each level were assessed over a ten-year period. Two applications are presented: analysis of crop protection strategies in horticulture and plant breeding programmes. When combined with four development models of organic farming, this multiâlevel analysis appears to be promising for defining research agendas
Quantum Information at the Interface of Light with Atomic Ensembles and Micromechanical Oscillators
This article reviews recent research towards a universal light-matter
interface. Such an interface is an important prerequisite for long distance
quantum communication, entanglement assisted sensing and measurement, as well
as for scalable photonic quantum computation. We review the developments in
light-matter interfaces based on room temperature atomic vapors interacting
with propagating pulses via the Faraday effect. This interaction has long been
used as a tool for quantum nondemolition detections of atomic spins via light.
It was discovered recently that this type of light-matter interaction can
actually be tuned to realize more general dynamics, enabling better performance
of the light-matter interface as well as rendering tasks possible, which were
before thought to be impractical. This includes the realization of improved
entanglement assisted and backaction evading magnetometry approaching the
Quantum Cramer-Rao limit, quantum memory for squeezed states of light and the
dissipative generation of entanglement. A separate, but related, experiment on
entanglement assisted cold atom clock showing the Heisenberg scaling of
precision is described. We also review a possible interface between collective
atomic spins with nano- or micromechanical oscillators, providing a link
between atomic and solid state physics approaches towards quantum information
processing
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