École Polytechnique Fédérale de Lausanne

About: École Polytechnique Fédérale de Lausanne is a facility organization based out in Lausanne, Switzerland. It is known for research contribution in the topics: Population & Catalysis. The organization has 44041 authors who have published 98296 publications receiving 4372092 citations. The organization is also known as: EPFL & ETHL.

Stimulating cooperation in self-organizing mobile ad hoc networks

Abstract: In military and rescue applications of mobile ad hoc networks, all the nodes belong to the same authority; therefore, they are motivated to cooperate in order to support the basic functions of the network In this paper, we consider the case when each node is its own authority and tries to maximize the benefits it gets from the network More precisely, we assume that the nodes are not willing to forward packets for the benefit of other nodes This problem may arise in civilian applications of mobile ad hoc networks In order to stimulate the nodes for packet forwarding, we propose a simple mechanism based on a counter in each node We study the behavior of the proposed mechanism analytically and by means of simulations, and detail the way in which it could be protected against misuse

Performance Analysis of the CONFIDANT Protocol: Cooperation Of Nodes - Fairness In Dynamic Ad-hoc NeTworks

Abstract: Mobile ad-hoc networking works properly only if the participating nodes cooperate in routing and forwarding. However, it may be advantageous for individual nodes not to cooperate. We propose a protocol, called CONFIDANT, for making misbehavior unattractive; it is based on selective altruism and utilitarianism. It aims at detecting and isolating misbehaving nodes, thus making it unattractive to deny cooperation. Trust relationships and routing decisions are based on experienced, observed, or reported routing and forwarding behavior of other nodes. The detailed implementation of CONFIDANT in this paper assumes that the network layer is based on the Dynamic Source Routing (DSR) protocol. We present a performance analysis of DSR fortified by CONFIDANT and compare it to regular defenseless DSR. It shows that a network with CONFIDANT and up to 60% of misbehaving nodes behaves almost as well as a benign network, in sharp contrast to a defenseless network. All simulations have been implemented and performed in GloMoSim.

Notch signalling controls pancreatic cell differentiation

Abstract: The pancreas contains both exocrine and endocrine cells, but the molecular mechanisms controlling the differentiation of these cell types are largely unknown. Despite their endodermal origin, pancreatic endocrine cells share several molecular characteristics with neurons, and, like neurons in the central nervous system, differentiating endocrine cells in the pancreas appear in a scattered fashion within a field of progenitor cells. This indicates that they may be generated by lateral specification through Notch signalling. Here, to test this idea, we analysed pancreas development in mice genetically altered at several steps in the Notch signalling pathway. Mice deficient for Delta-like gene 1 (Dll1) or the intracellular mediator RBP-JK showed accelerated differentiation of pancreatic endocrine cells. A similar phenotype was observed in mice over-expressing neurogenin 3(ngn 3) or the intracellular form of Notch3 (ref. 13) (a repressor of Notch signalling). These data provide evidence that ngn3 acts as pro-endocrine gene and that Notch signalling is critical for the decision between theendocrine and progenitor/exocrine fates in the developing pancreas.

Contributions of cultural services to the ecosystem services agenda.

Abstract: Cultural ecosystem services (ES) are consistently recognized but not yet adequately defined or integrated within the ES framework. A substantial body of models, methods, and data relevant to cultural services has been developed within the social and behavioral sciences before and outside of the ES approach. A selective review of work in landscape aesthetics, cultural heritage, outdoor recreation, and spiritual significance demonstrates opportunities for operationally defining cultural services in terms of socioecological models, consistent with the larger set of ES. Such models explicitly link ecological structures and functions with cultural values and benefits, facilitating communication between scientists and stakeholders and enabling economic, multicriterion, deliberative evaluation and other methods that can clarify tradeoffs and synergies involving cultural ES. Based on this approach, a common representation is offered that frames cultural services, along with all ES, by the relative contribution of relevant ecological structures and functions and by applicable social evaluation approaches. This perspective provides a foundation for merging ecological and social science epistemologies to define and integrate cultural services better within the broader ES framework.

Highly Efficient Light-Harvesting Ruthenium Sensitizer for Thin-Film Dye-Sensitized Solar Cells

Abstract: A high molar extinction coefficient heteroleptic ruthenium complex, incorporating an electron-rich hexylthio-terminal chain, has been synthesized and demonstrated as an efficient sensitizer for dye...