The Experts below are selected from a list of 142887 Experts worldwide ranked by ideXlab platform
D Lenstra - One of the best experts on this subject based on the ideXlab platform.
-
the dynamical complexity of optically injected semiconductor lasers
Physics Reports, 2005Co-Authors: Sebastian Wieczorek, Bernd Krauskopf, T B Simpson, D LenstraAbstract:Abstract This report presents a modern approach to the theoretical and experimental study of complex nonlinear behavior of a semiconductor laser with optical injection—an example of a widely applied and technologically relevant forced nonlinear oscillator. We show that the careful Bifurcation analysis of a rate equation model yields (i) a deeper understanding of already studied physical phenomena, and (ii) the discovery of new dynamical effects, such as multipulse excitability. Different instabilities, cascades of Bifurcations, multistability, and sudden chaotic transitions, which are often viewed as independent, are in fact logically connected into a consistent web of Bifurcations via special points called organizing centers. This theoretical Bifurcation analysis has predictive power, which manifests itself in good agreement with experimental measurements over a wide range of parameters and diversity of dynamics. While it is dealing with the specific system of an optically injected laser, our work constitutes the state-of-the-art in the understanding and modeling of a nonlinear physical system in general.
Antonio Colombo - One of the best experts on this subject based on the ideXlab platform.
-
Bifurcation stenting current strategies and new devices
Heart, 2009Co-Authors: Azeem Latib, Antonio Colombo, Giuseppe SangiorgiAbstract:Based on the results of numerous randomised trials, the provisional approach of implanting one stent on the main branch has become the default approach to most Bifurcation lesions. However, Bifurcation intervention still remains technically challenging. Dedicated Bifurcation stents have been designed to specifically treat coronary Bifurcations with the aim of dealing with some of the shortcomings of the conventional percutaneous approach to Bifurcation intervention. Most of the devices are aimed at facilitating the provisional approach. They are an exciting and innovative technology that may further simplify the management and current approach to Bifurcation treatment. Currently, 11 devices are available that have either completed or are currently undergoing First-In-Man trials. The development of more drug-eluting platforms and larger studies with control groups demonstrating their clinical applicability, efficacy and safety are required before they are widely incorporated into daily practice.
-
Bifurcation disease what do we know what should we do
Jacc-cardiovascular Interventions, 2008Co-Authors: Azeem Latib, Antonio ColomboAbstract:The percutaneous treatment of coronary Bifurcations has moved past an important milestone in that the 1- versus 2-stent debate appears to have been resolved. The provisional approach of implanting one stent on the main branch should be the default approach in most Bifurcations lesions. Selection of the most appropriate strategy for an individual Bifurcation is important. Some Bifurcations require 1 stent, whereas others require the stenting of both branches. Irrespective of whether a 1- or 2-stent strategy is chosen, the results after Bifurcation percutaneous coronary intervention (PCI) have dramatically improved. Dedicated Bifurcation stents are an exciting new technology that may further simplify the management of Bifurcation PCI and change some of these concepts.
-
the clinical outcome of percutaneous treatment of Bifurcation lesions in multivessel coronary artery disease with the sirolimus eluting stent insights from the arterial revascularization therapies study part ii arts ii
European Heart Journal, 2007Co-Authors: Keiichi Tsuchida, Antonio Colombo, Thierry Lefevre, Keith G Oldroyd, Victo Guetta, Giulio Guagliumi, Wolfgang Von Scheid, Witold Ruzyllo, Christia W Hamm, Marco EssersAbstract:Aims Little is known about the impact of treating Bifurcations on the overall outcome of multivessel coronary artery disease treated with stenting. This analysis was made to investigate the 1 year clinical outcome of the treatment of Bifurcation lesions using sirolimus-eluting stents (SES) in patients with multivessel disease. Methods and results Among a total of 607 patients (2160 lesions) in the Arterial Revascularization Therapies Study part II (ARTS II), there were 324 patients in whom at least one Bifurcation lesion was treated (465 lesions). Patients with Bifurcations were compared with those without Bifurcations in terms of baseline characteristics and major adverse cardiac and cerebrovascular events (MACCE). Patients with ‘true’ (200 patients) vs. ‘partial’ Bifurcations (124 patients) and usage of a one- (263 patients) vs. two-stent strategy (61 patients) were also evaluated. The Bifurcation group was associated with more complex lesion and procedural characteristics than the non-Bifurcation group. However, there was no significant difference in 1 year MACCE rates between the Bifurcation group and the non-Bifurcation group (13.3 vs. 11.0%, P = 0.46). MACCE in patients with true Bifurcations was 13.0 vs. 13.7% for partial Bifurcations ( P = 0.87) and 14.1 vs. 9.8% for one- vs. two-stent strategy ( P = 0.53). Conclusions In this trial without angiographic follow-up, the presence of Bifurcations did not affect 1 year outcomes after SES implantation. The outcomes in true vs. partial Bifurcations and using one vs. two stents were similar when the treatment strategies were left to the operator's discretion.
-
a new dedicated stent and delivery system for the treatment of Bifurcation lesions preliminary experience
Catheterization and Cardiovascular Interventions, 2003Co-Authors: Konstantinos Toutouzas, Goran Stankovic, Remo Albiero, Takuro Takagi, Nicola Corvaja, Caterina Milici, Carlo Di Mario, Leo Finci, Antonio ColomboAbstract:We report the first clinical experience in eight patients with a new stent and delivery system specifically designed for the treatment of Bifurcational lesions. The device (AST SLK-View system) consists of a premounted stent and a delivery system. The stent has a side aperture, which orients toward the ostium of the side branch. The system allows deployment of the stent while the access to both main and side branches is maintained by two wires. We evaluated this system in nine Bifurcations. The location of Bifurcations was left descending artery/diagonal branch in four lesions, left circumflex/obtuse marginal branch in three lesions, and postero-lateral branch/posterior descending artery in two lesions. Predilation was performed in six lesions of the main branches and in five lesions of the side branches. The stent was effectively delivered to all Bifurcations except for one, in which the target lesion was located at a distal segment and the device could not be delivered. Following stent implantation in the main branch, two lesions at the side branches were treated by stent, while the other lesions were treated by balloon angioplasty without difficulty. Final kissing balloon was performed in four Bifurcation lesions. No adverse event was observed during 1 month of clinical follow-up. Treatment of Bifurcation lesions with this new dedicated device appears to be feasible. This new device may introduce a new approach for the treatment of coronary Bifurcation lesions. Cathet Cardiovasc Intervent 2003;58:34–42. © 2003 Wiley-Liss, Inc.
Bernd Krauskopf - One of the best experts on this subject based on the ideXlab platform.
-
the dynamical complexity of optically injected semiconductor lasers
Physics Reports, 2005Co-Authors: Sebastian Wieczorek, Bernd Krauskopf, T B Simpson, D LenstraAbstract:Abstract This report presents a modern approach to the theoretical and experimental study of complex nonlinear behavior of a semiconductor laser with optical injection—an example of a widely applied and technologically relevant forced nonlinear oscillator. We show that the careful Bifurcation analysis of a rate equation model yields (i) a deeper understanding of already studied physical phenomena, and (ii) the discovery of new dynamical effects, such as multipulse excitability. Different instabilities, cascades of Bifurcations, multistability, and sudden chaotic transitions, which are often viewed as independent, are in fact logically connected into a consistent web of Bifurcations via special points called organizing centers. This theoretical Bifurcation analysis has predictive power, which manifests itself in good agreement with experimental measurements over a wide range of parameters and diversity of dynamics. While it is dealing with the specific system of an optically injected laser, our work constitutes the state-of-the-art in the understanding and modeling of a nonlinear physical system in general.
Guy Theraulaz - One of the best experts on this subject based on the ideXlab platform.
-
do ants need to estimate the geometrical properties of trail Bifurcations to find an efficient route a swarm robotics test bed
PLOS Computational Biology, 2013Co-Authors: Simon Garnier, Maud Combe, Christian Jost, Guy TheraulazAbstract:Interactions between individuals and the structure of their environment play a crucial role in shaping self-organized collective behaviors. Recent studies have shown that ants crossing asymmetrical Bifurcations in a network of galleries tend to follow the branch that deviates the least from their incoming direction. At the collective level, the combination of this tendency and the pheromone-based recruitment results in a greater likelihood of selecting the shortest path between the colony's nest and a food source in a network containing asymmetrical Bifurcations. It was not clear however what the origin of this behavioral bias is. Here we propose that it results from a simple interaction between the behavior of the ants and the geometry of the network, and that it does not require the ability to measure the angle of the Bifurcation. We tested this hypothesis using groups of ant-like robots whose perceptual and cognitive abilities can be fully specified. We programmed them only to lay down and follow light trails, avoid obstacles and move according to a correlated random walk, but not to use more sophisticated orientation methods. We recorded the behavior of the robots in networks of galleries presenting either only symmetrical Bifurcations or a combination of symmetrical and asymmetrical Bifurcations. Individual robots displayed the same pattern of branch choice as individual ants when crossing a Bifurcation, suggesting that ants do not actually measure the geometry of the Bifurcations when travelling along a pheromone trail. Finally at the collective level, the group of robots was more likely to select one of the possible shorter paths between two designated areas when moving in an asymmetrical network, as observed in ants. This study reveals the importance of the shape of trail networks for foraging in ants and emphasizes the underestimated role of the geometrical properties of transportation networks in general.
Simon Garnier - One of the best experts on this subject based on the ideXlab platform.
-
do ants need to estimate the geometrical properties of trail Bifurcations to find an efficient route a swarm robotics test bed
PLOS Computational Biology, 2013Co-Authors: Simon Garnier, Maud Combe, Christian Jost, Guy TheraulazAbstract:Interactions between individuals and the structure of their environment play a crucial role in shaping self-organized collective behaviors. Recent studies have shown that ants crossing asymmetrical Bifurcations in a network of galleries tend to follow the branch that deviates the least from their incoming direction. At the collective level, the combination of this tendency and the pheromone-based recruitment results in a greater likelihood of selecting the shortest path between the colony's nest and a food source in a network containing asymmetrical Bifurcations. It was not clear however what the origin of this behavioral bias is. Here we propose that it results from a simple interaction between the behavior of the ants and the geometry of the network, and that it does not require the ability to measure the angle of the Bifurcation. We tested this hypothesis using groups of ant-like robots whose perceptual and cognitive abilities can be fully specified. We programmed them only to lay down and follow light trails, avoid obstacles and move according to a correlated random walk, but not to use more sophisticated orientation methods. We recorded the behavior of the robots in networks of galleries presenting either only symmetrical Bifurcations or a combination of symmetrical and asymmetrical Bifurcations. Individual robots displayed the same pattern of branch choice as individual ants when crossing a Bifurcation, suggesting that ants do not actually measure the geometry of the Bifurcations when travelling along a pheromone trail. Finally at the collective level, the group of robots was more likely to select one of the possible shorter paths between two designated areas when moving in an asymmetrical network, as observed in ants. This study reveals the importance of the shape of trail networks for foraging in ants and emphasizes the underestimated role of the geometrical properties of transportation networks in general.
