373 results on '"Lacan, P."'
Search Results
2. The potential seismic hazard of the Tarímbaro-Álvaro Obregón fault, a major structure of the Morelia-Acambay fault system in central México
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Gómez-Vasconcelos, Martha Gabriela, Avellán, Denis Ramón, García, Jesús Avila, Lacan, Pierre, Israde-Alcántara, Isabel, García, Oscar, Castellano, Jélime Aray, and Audin, Laurence
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- 2024
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3. Online Proactive Multi-Task Assignment with Resource Availability Anticipation
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Nedelmann, Déborah Conforto, Lacan, Jérôme, and Chanel, Caroline
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Computer Science - Multiagent Systems ,Computer Science - Performance - Abstract
With the emergence of services and online applications as taxi dispatching, crowdsourcing, package or food delivery, industrials and researchers are paying attention to the online multi-task assignment optimization field to quickly and efficiently met demands. In this context, this paper is interested in the multi-task assignment problem where multiple requests (e.g. tasks) arrive over time and must be dynamically matched to (mobile) agents. This optimization problem is known to be NP-hard. In order to treat this problem with a proactive mindset, we propose to use a receding-horizon approach to determine which resources (e.g. taxis, mobile agents, drones, robots) would be available within this (possibly dynamic) receding-horizon to meet the current set of requests (i.e. tasks) as good as possible. Contrarily to several works in this domain, we have chosen to make no assumption concerning future locations of requests. To achieve fast optimized online solutions in terms of costs and amount of allocated tasks, we have designed a genetic algorithm based on a fitness function integrating the traveled distance and the age of the requests. We compared our proactive multi-task assignment with resource availability anticipation approach with a classical reactive approach. The results obtained in two benchmark problems, one synthetic and another based on real data, show that our resource availability anticipation method can achieve better results in terms of costs (e.g. traveled distance) and amount of allocated tasks than reactive approaches while decreasing resources idle time., Comment: In Proceedings AREA 2023, arXiv:2310.00333
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- 2023
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4. Modular zk-Rollup On-Demand
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Lavaur, Thomas, Detchart, Jonathan, Lacan, Jérôme, and Chanel, Caroline P. C.
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Computer Science - Cryptography and Security - Abstract
The rapid expansion of the use of blockchain-based systems often leads to a choice between customizable private blockchains and more secure, scalable and decentralized but expensive public blockchains. This choice represents the trade-off between privacy and customization at a low cost and security, scalability, and a large user base but at a high cost. In order to improve the scalability of secure public blockchains while enabling privacy and cost reduction, zk-rollups, a layer 2 solution, appear to be a promising avenue. This paper explores the benefits of zk-rollups, including improved privacy, as well as their potential to support transactions designed for specific applications. We propose an innovative design that allows multiple zk-rollups to co-exist on the same smart contracts, simplifying their creation and customization. We then evaluate the first implementation of our system highlighting a low overhead on existing transaction types and on proof generation while strongly decreasing the cost of new transaction types and drastically reducing zk-rollup creation costs., Comment: url : https://www.sciencedirect.com/science/article/pii/S1084804523000978
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- 2023
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5. Bone marrow graft versus peripheral blood graft in haploidentical hematopoietic stem cells transplantation: a retrospective analysis in1344 patients of SFGM-TC registry
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Lacan, Claire, Lambert, Jérôme, Forcade, Edouard, Robin, Marie, Chevallier, Patrice, Loron, Sandrine, Bulabois, Claude-Éric, Orvain, Corentin, Ceballos, Patrice, Daguindau, Etienne, Charbonnier, Amandine, Chalandon, Yves, Bernard, Marc, Simand, Célestine, Rubio, Marie-Thérèse, Turlure, Pascal, Maertens, Johan, Huynh, Anne, Loschi, Michael, Bay, Jacques-Olivier, Guillerm, Gaëlle, Alani, Mustafa, Castilla-Llorente, Cristina, Poiré, Xavier, Chantepie, Sylvain, Maillard, Natacha, Beguin, Yves, Marçais, Ambroise, Cornillon, Jérôme, Malfuson, Jean-Valère, Maury, Sébastien, Meuleman, Nathalie, Villate, Alban, Bekadja, Mohammed-Amine, Walter-Petrich, Anouk, Jacque, Nathalie, Srour, Micha, Devillier, Raynier, and Nguyen, Stéphanie
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- 2024
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6. Bone marrow graft versus peripheral blood graft in haploidentical hematopoietic stem cells transplantation: a retrospective analysis in1344 patients of SFGM-TC registry
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Claire Lacan, Jérôme Lambert, Edouard Forcade, Marie Robin, Patrice Chevallier, Sandrine Loron, Claude-Éric Bulabois, Corentin Orvain, Patrice Ceballos, Etienne Daguindau, Amandine Charbonnier, Yves Chalandon, Marc Bernard, Célestine Simand, Marie-Thérèse Rubio, Pascal Turlure, Johan Maertens, Anne Huynh, Michael Loschi, Jacques-Olivier Bay, Gaëlle Guillerm, Mustafa Alani, Cristina Castilla-Llorente, Xavier Poiré, Sylvain Chantepie, Natacha Maillard, Yves Beguin, Ambroise Marçais, Jérôme Cornillon, Jean-Valère Malfuson, Sébastien Maury, Nathalie Meuleman, Alban Villate, Mohammed-Amine Bekadja, Anouk Walter-Petrich, Nathalie Jacque, Micha Srour, Raynier Devillier, and Stéphanie Nguyen
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Haploidentical hematopoietic stem cell transplantation ,Graft source ,Bone marrow ,Peripheral stem cell ,Anti-thymoglobulin ,Diseases of the blood and blood-forming organs ,RC633-647.5 ,Neoplasms. Tumors. Oncology. Including cancer and carcinogens ,RC254-282 - Abstract
Abstract The use of peripheral blood (PB) or bone marrow (BM) stem cells graft in haploidentical hematopoietic stem cell transplantation with post-transplant cyclophosphamide (PTCy) for graft-versus-host disease (GVHD) prophylaxis remains controversial. Moreover, the value of adding anti-thymoglobulin (ATG) to PTCy is unknown. A total of 1344 adult patients received an unmanipulated haploidentical transplant at 37 centers from 2012 to 2019 for hematologic malignancy. We compared the outcomes of patients according to the type of graft, using a propensity score analysis. In total population, grade II–IV and III–IV acute GVHD (aGVHD) were lower with BM than with PB. Grade III–IV aGVHD was lower with BM than with PB + ATG. All outcomes were similar in PB and PB + ATG groups. Then, in total population, adding ATG does not benefit the procedure. In acute leukemia, myelodysplastic syndrome and myeloproliferative syndrome (AL-MDS-MPS) subgroup receiving non-myeloablative conditioning, risk of relapse was twice greater with BM than with PB (51 vs. 22%, respectively). Conversely, risk of aGVHD was greater with PB (38% for aGVHD II–IV; 16% for aGVHD III–IV) than with BM (28% for aGVHD II–IV; 8% for aGVHD III–IV). In this subgroup with intensified conditioning regimen, risk of relapse became similar with PB and BM but risk of aGVHD III–IV remained higher with PB than with BM graft (HR = 2.0; range [1.17–3.43], p = 0.012).
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- 2024
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7. Simplifying Forwarding Data Plane Operations with XOR-Based Source Routing
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Lacan, Jérôme and Lochin, Emmanuel
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- 2024
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8. Anne-Catherine Schmidt-Trimborn, La Ligue d’Action française (1905-1936). Organisations, lieux et pratiques militantes
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Baptiste Roger-Lacan
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History (General) and history of Europe - Published
- 2024
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9. Fetal brain response to worsening acidosis: an experimental study in a fetal sheep model of umbilical cord occlusions
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Laure Lacan, Charles Garabedian, Julien De Jonckheere, Louise Ghesquiere, Laurent Storme, Dyuti Sharma, and Sylvie Nguyen The Tich
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Medicine ,Science - Abstract
Abstract Perinatal anoxia remains an important public health problem as it can lead to hypoxic–ischaemic encephalopathy (HIE) and cause significant neonatal mortality and morbidity. The mechanisms of the fetal brain’s response to hypoxia are still unclear and current methods of in utero HIE prediction are not reliable. In this study, we directly analysed the brain response to hypoxia in fetal sheep using in utero EEG. Near-term fetal sheep were subjected to progressive hypoxia induced by repeated umbilical cord occlusions (UCO) at increasing frequency. EEG changes during and between UCO were analysed visually and quantitatively, and related with gasometric and haemodynamic data. EEG signal was suppressed during occlusions and progressively slowed between occlusions with the increasing severity of the occlusions. Per-occlusion EEG suppression correlated with per-occlusion bradycardia and increased blood pressure, whereas EEG slowing and amplitude decreases correlated with arterial hypotension and respiratory acidosis. The suppression of the EEG signal during cord occlusion, in parallel with cardiovascular adaptation could correspond to a rapid cerebral adaptation mechanism that may have a neuroprotective role. The progressive alteration of the signal with the severity of the occlusions would rather reflect the cerebral hypoperfusion due to the failure of the cardiovascular adaptation mechanisms.
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- 2023
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10. Deep Transfer Learning for Blended Source Identification in Galaxy Survey Data
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Farrens, S., Lacan, A., Guinot, A., and Vitorelli, A. Z.
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Astrophysics - Instrumentation and Methods for Astrophysics ,Astrophysics - Cosmology and Nongalactic Astrophysics - Abstract
We present BlendHunter, a proof-of-concept for a deep transfer learning based approach for the automated and robust identification of blended sources in galaxy survey data. We take the VGG-16 network with pre-trained convolutional layers and train the fully connected layers on parametric models of COSMOS images. We test the efficacy of the transfer learning by taking the weights learned on the parametric models and using them to identify blends in more realistic CFIS-like images. We compare the performance of this method to SEP (a Python implementation of SExtractor) as function of noise level and the separation between sources. We find that BlendHunter outperforms SEP by $\sim 15\%$ in terms of classification accuracy for close blends ($<10$ pixel separation between sources) regardless of the noise level used for training. Additionally, the method provides consistent results to SEP for distant blends ($\geq10$ pixel separation between sources) provided the network is trained on data with a relatively close noise standard deviation to the target images. The code and data have been made publicly available to ensure the reproducibility of the results., Comment: 9 pages, 6 figures, accepted for publication in A&A
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- 2021
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11. Intensity Prediction Equations Based on the Environmental Seismic Intensity (ESI-07) Scale: Application to Normal Fault Earthquakes
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Marco Pizza, Francesca Ferrario, Alessandro M. Michetti, M. Magdalena Velázquez-Bucio, Pierre Lacan, and Sabina Porfido
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intensity attenuation ,ESI-07 scale ,intensity prediction equations ,earthquake ,normal fault ,Technology ,Engineering (General). Civil engineering (General) ,TA1-2040 ,Biology (General) ,QH301-705.5 ,Physics ,QC1-999 ,Chemistry ,QD1-999 - Abstract
Earthquake environmental effects may significantly contribute to the damage caused by seismic events; similar to ground motion, the environmental effects are globally stronger in the vicinity and decrease moving away from the epicenter or seismogenic source. To date, a single intensity prediction equation (IPE) has been proposed in the Italian Apennines for intensity scale dealings with environmental effects: the Environmental Seismic Intensity (ESI-07). Here, we evaluate the sensitivity of the IPE with respect to input data and methodological choices and we propose IPEs with global validity for crustal normal faults. We show the strong influence of input data on the obtained attenuation investigating the 1980 Irpinia–Basilicata (Southern Italy) earthquake. We exploit a dataset of 26 earthquakes to build an IPE considering the epicentral distance. We also propose an IPE considering the distance from the fault rupture, which is derived from a dataset of 10 earthquakes. The proposed equations are valid for normal faults up to 40 km from the epicenter/fault and may flank other models predicting ground motion or damage to the built environment. Our work thus contributes to the use of the ESI-07 scale for hazard purposes.
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- 2024
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12. Fetal brain response to worsening acidosis: an experimental study in a fetal sheep model of umbilical cord occlusions
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Lacan, Laure, Garabedian, Charles, De Jonckheere, Julien, Ghesquiere, Louise, Storme, Laurent, Sharma, Dyuti, and Nguyen The Tich, Sylvie
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- 2023
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13. Endometriosis, infertility and occupational life: women's plea for recognition
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Gremillet, Letizia, Netter, Antoine, Sari-Minodier, Irène, Miquel, Laura, Lacan, Arnaud, and Courbiere, Blandine
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- 2023
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14. Using Homomorphic hashes in coded blockchains
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Perard, Doriane, Goffin, Xavier, and Lacan, Jérôme
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Computer Science - Cryptography and Security - Abstract
One of the scalability issues of blockchains is the increase of their sizes which can prevent users from storing them and thus from contributing to the decentralization effort. Recent works developed the concept of coded blockchains, which allow users to store only some coded fragments of the blockchains. However, this solution is not protected against malicious nodes that can propagate erroneous coded fragments. We propose in the paper to add homomorphic hashes to this system. This allows for instantaneous detection of erroneous fragments and thus avoids decoding with wrong data. We describe the integration of this mechanism in coded blockchains and we evaluate its complexity theoretically and by simulation., Comment: arXiv admin note: text overlap with arXiv:1805.00860
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- 2020
15. BlockHouse: Blockchain-based Distributed Storehouse System
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Perard, Doriane, Gicquel, Lucas, and Lacan, Jérôme
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Computer Science - Cryptography and Security ,Computer Science - Distributed, Parallel, and Cluster Computing - Abstract
We propose in this paper BlockHouse, a decentralized/P2P storage system fully based on private blockchains. Each participant can rent his unused storage in order to host data of other members. This system uses a dual Smart Contract and Proof of Retrievability system to automatically check at a fixed frequency if the file is still hosted. In addition to transparency, the blockchain allows a better integration with all payments associated to this type of system ( regular payments, sequestration to ensure good behaviors of users, ...). Except the data transferred between the client and the server, all the actions go through a smart contract in the blockchain in order to log, pay and secure the entire storage process., Comment: Published in "9TH Latin-American Symposium on Dependable Computing", 2019
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- 2020
16. XOR-based Source Routing
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Lacan, Jérôme and Lochin, Emmanuel
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Computer Science - Networking and Internet Architecture - Abstract
We introduce a XOR-based source routing (XSR) scheme as a novel approach to enable fast forwarding and low-latency communications. XSR uses linear encoding operation to both 1)~build the path labels of unicast and multicast data transfers; 2)~perform fast computational efficient routing decisions compared to standard table lookup procedure without any packet modification all along the path. XSR specifically focuses on decreasing the complexity of forwarding router operations. This allows packet switches (e.g, link-layer switch or router) to perform only simple linear operations over a binary vector label which embeds the path. XSR provides the building blocks to speed up the forwarding plane and can be applied to different data planes such as MPLS or IPv6. Compared to recent approaches based on modular arithmetic, XSR computes the smallest label possible and presents strong scalable properties allowing to be deployed over any kind of core vendor or datacenter networks. At last but not least, the same computed label can be used interchangeably to cross the path forward or reverse in the context of unicast communication.
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- 2020
17. Endometriosis, infertility and occupational life: women's plea for recognition
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Letizia Gremillet, Antoine Netter, Irène Sari-Minodier, Laura Miquel, Arnaud Lacan, and Blandine Courbiere
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Endometriosis ,Qualitative study ,In vitro fertilization ,Gynecology and obstetrics ,RG1-991 ,Public aspects of medicine ,RA1-1270 - Abstract
Abstract The objective of this study was to explore and describe the specificities of the occupational life of infertile endometriotic women treated by in vitro fertilization. We conducted a qualitative monocentric study between December 2020 and June 2021. Twelve semi-structured in-depth interviews using a theme-based interview guide with open questions were undertaken with infertile women with deep infiltrating endometriosis. Data analysis was conducted using an inductive approach according to the grounded theory method. Three main themes emerged from the interviews: (i) barriers to reconciling illness and work life, (ii) facilitating factors for well-being at work, and (iii) consequences and outlooks. It appeared that the time of infertility treatment represents a particular period of change in the working lives of women with endometriosis. For most women, these changes are experienced negatively, often with a renunciation of goals. For others, this is the time to communicate the difficulties linked to their illness to their professional entourage. There is a long path ahead to finally achieving recognition of endometriosis in the context of professional life.
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- 2023
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18. CAR T-cell therapy for central nervous system lymphomas: blood and cerebrospinal fluid biology, and outcomes
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Claire Lacan, Jonathan Caron, Nadine Tarantino, Baptiste Fouquet, Mustapha Cherai, Christophe Parizot, Véronique Morel, Laetitia Souchet, Madalina Uzunov, Guy Gorochov, Stéphanie Nguyen-Quoc, Elise Sourdeau, Vincent Vieillard, Makoto Miyara, Angélique Vinit, Silvia Solorzano, Carole Soussain, Caroline Houillier, Carole Metz, Brigitte Autran, Elena Litvinova, Magali Le Garff-Tavernier, Françoise Norol, Damien Roos-Weil, Sylvan Choquet, Amélie Guihot, and Marine Baron
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Diseases of the blood and blood-forming organs ,RC633-647.5 - Published
- 2023
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19. Erasure code-based low storage blockchain node
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Perard, Doriane, Lacan, Jérôme, Bachy, Yann, and Detchart, Jonathan
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Computer Science - Cryptography and Security ,Computer Science - Distributed, Parallel, and Cluster Computing - Abstract
The concept of a decentralized ledger usually implies that each node of a blockchain network stores the entire blockchain. However, in the case of popular blockchains, which each weigh several hundreds of GB, the large amount of data to be stored can incite new or low-capacity nodes to run lightweight clients. Such nodes do not participate to the global storage effort and can result in a centralization of the blockchain by very few nodes, which is contrary to the basic concepts of a blockchain. To avoid this problem, we propose new low storage nodes that store a reduced amount of data generated from the blockchain by using erasure codes. The properties of this technique ensure that any block of the chain can be easily rebuild from a small number of such nodes. This system should encourage low storage nodes to contribute to the storage of the blockchain and to maintain decentralization despite of a globally increasing size of the blockchain. This system paves the way to new types of blockchains which would only be managed by low capacity nodes.
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- 2018
20. Pierre Gaxotte, ou l’extrême droite respectable
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Baptiste Roger-Lacan
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historiography ,fascism ,counter-revolution ,royalism ,Gaxotte ,far right ,History (General) and history of Europe - Abstract
The biography of Pierre Gaxotte questions the « far-right » as a category. As a journalist, editor and historian, Pierre Gaxotte wrote an abundant and protean work and was one of the leading figures of the French far-right for six decades, having multiple commitments, from being an editor at the Action Française in the 1920’s to the patronage of the journal Nouvelle École in the late 1970s. His itinerary is all the more intriguing since he was able - through a thorough work of biographical reconstruction - to escape the anathema that struck the French far-right after 1945. Subsequently, he was able to impose the image of a worldly and respectable reactionary, a true notable of Parisian letters, allowing him to constitute a discreet bridge between a rebuilding intellectual extreme right and the general conservative public, as evidenced in particular by the undeniable success of his most famous work, La Révolution française (1928).
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- 2022
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21. New perspectives in studying active faults in metropolitan France: the 'Active faults France' (FACT/ATS) research axis from the Resif-Epos consortium
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Ritz, Jean-François, Baize, Stéphane, Audin, Laurence, Authémayou, Christine, Graveleau, Fabien, Kaub, Caroline, Lacan, Pierre, Leclerc, Frédérique, Larroque, Christophe, Manchuel, Kevin, Mugnier, Jean-Louis, Ortuño, Maria, Rizza, Magali, Vassallo, Riccardo, Antoine, Pierre, Arroucau, Pierre, Billant, Jérémy, Bollinger, Laurent, Ferry, Matthieu, Fillon, Charlotte, Geoffroy, Laurent, Jomard, Hervé, Le Roy, Pascal, Locht, Jean-Luc, Migeon, Sébastien, Perrin, Clément, Perrot, Julie, Ratzov, Gueorgui, Reicherter, Klaus, Soubigou, Olivier, Vergniault, Christophe, Viaplana-Muzas, Marc, and Van der Woerd, Jérôme
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FACT research axis (ATS-RESIF) ,Mainland France ,Active fault ,Paleoseismogy ,Earthquake geology ,Stable continental region ,Plate interior ,Geophysics. Cosmic physics ,QC801-809 ,Chemistry ,QD1-999 ,Geology ,QE1-996.5 - Abstract
Mainland France is part of a plate interior with a strong structural heritage, undergoing a low rate of deformation, where destructive earthquakes can nevertheless occur. In this paper, we emphasize that the knowledge of active faults is still largely fragmentary, and that significant efforts are needed to generate robust data, in particular on the numerous faults, that still lack any study. This is the aim of the “Failles ACTives France” (FACT) axis launched in the framework of the Transverse Seismicity Action (ATS) of the Resif-Epos consortium. We present some recent investigations carried out along suspected active faults in mountainous areas, their forelands and remote lowlands, which implement new approaches and new tools, and allow characterizing their Quaternary activity.
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- 2022
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22. Improving the coding speed of erasure codes with polynomial ring transforms
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Detchart, Jonathan and Lacan, Jérôme
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Computer Science - Information Theory - Abstract
Erasure codes are widely used in today's storage systems to cope with failures. Most of them use the finite field arithmetic. In this paper, we propose an implementation and a coding speed evaluation of an original method called PYRIT (PolYnomial RIng Transform) to perform operations between elements of a finite field into a bigger ring by using fast transforms between these two structures. Working in such a ring is much easier than working in a finite field. Firstly, it reduces the coding complexity by design. Secondly, it allows simple but efficient \texttt{xor}-based implementations by unrolling the operations thanks to the properties of the ring structure. We evaluate this proposition for Maximum Distance Separable erasure codes and we show that our method has better performances than common codes. Compared to the best known implementations, the coding speeds are increased by a factor varying from $1.5$ to $2$.
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- 2017
23. Fast Xor-based Erasure Coding based on Polynomial Ring Transforms
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Detchart, Jonathan and Lacan, Jérôme
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Computer Science - Information Theory - Abstract
The complexity of software implementations of MDS erasure codes mainly depends on the efficiency of the finite field operations implementation. In this paper, we propose a method to reduce the complexity of the finite field multiplication by using fast transforms between a field and a ring to perform the multiplication in a ring. We show that moving to a ring reduces the complexity of the operations. Then, we show that this construction allows the use of simple scheduling to reduce the number of operations.
- Published
- 2017
24. Mechanical Properties and Liquid Absorption of Calcium Phosphate Composite Cements
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Ioana Lacan, Marioara Moldovan, Codruta Sarosi, Stanca Cuc, Mihaela Pastrav, Ioan Petean, and Razvan Ene
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calcium phosphate ,chitosan ,composite cements ,mechanical properties ,Technology ,Electrical engineering. Electronics. Nuclear engineering ,TK1-9971 ,Engineering (General). Civil engineering (General) ,TA1-2040 ,Microscopy ,QH201-278.5 ,Descriptive and experimental mechanics ,QC120-168.85 - Abstract
Calcium phosphate cements present increased biocompatibility due to their chemical composition being similar to that of the hydroxyapatite in the hard tissues of the living body. It has certain limitations due to its poor mechanical properties, such as low tensile strength and increased brittleness. Thus, the optimal way to improve properties is through the design of novel composite cements. The purpose was fulfilled using a 25% hydroxyethyl methacrylate (HEMA) mixed with 3% urethane dimethacrzlate (UDMA) base matrix with various ratios of polyethylene glycol (PEG 400) and polycaprolactone (PCL). Mineral filler is based on tricalcium phosphate (TCP) with different chitosan ratio used as bio-response enhancer additive. Four mixtures were prepared: S0—unfilled polymer matrix; S1 with 50% TCP filler; S2 with 50% chitosan + TCP filler; and S3 with 17.5% chitosan + TCP mixed with 17.5% nano hydroxyapatite (HA). The mechanical properties testing revealed that the best compressive strength was obtained by S2, followed by S3, and the worst value was obtained for the unfilled matrix. The same tendency was observed for tensile and flexural strength. These results show that the novel filler system increases the mechanical resistance of the TCP composite cements. Liquid exposure investigation reveals a relative constant solubility of the used filler systems during 21 days of exposure: the most soluble fillers being S3 and S2 revealing that the additivated TCP is more soluble than without additives ones. Thus, the filler embedding mode into the polymer matrix plays a key role in the liquid absorption. It was observed that additive filler enhances the hydrophobicity of UDMA monomer, with the matrix resulting in the lowest liquid absorption values, while the non-additivated samples are more absorbent due to the prevalence of hydrolytic aliphatic groups within PEG 400. The higher liquid absorption was obtained on the first day of immersion, and it progressively decreased with exposure time due to the relative swelling of the surface microstructural features. The obtained results are confirmed by the microstructural changes monitored by SEM microscopy. S3 and S2 present a very uniform and compact filler distribution, while S1 presents local clustering of the TCP powder at the contact with the polymer matrix. The liquid exposure revealed significant pore formation in S0 and S1 samples, while S3 and S2 proved to be more resistant against superficial erosion, proving the best resistance against liquid penetration.
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- 2023
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25. Evaluation of monitoring tools for WASH response in a cholera outbreak in northeast Nigeria
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Marine Ricau, Lise Lacan, Emmanuel Ihemezue, Daniele Lantagne, and Gabrielle String
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cholera ,data collection ,humanitarian context ,monitoring ,nigeria ,wash ,Environmental technology. Sanitary engineering ,TD1-1066 - Abstract
Monitoring water, sanitation, and hygiene programs in cholera outbreaks is critical to improve humanitarian response. The objective of this research was to evaluate, and improve, WASH in cholera monitoring tools currently used in northeast Nigeria. We collected 723 forms from 2019 from three form types, combined them into one database of 980 activities, and stratified data by form type, response, implementing organization, activity, month/day, and geographical area. We conducted seven key informant interviews (KIIs) with monitoring tool users and decision-makers. Data irregularities (including in design, collection, and entry) led to an inability to meaningfully analyze monitoring forms. In KIIs, eight themes emerged: ease of use of current tools, improvement in monitoring over time, lack of access to data, need for training, inconsistent reporting practices, need for modification of current questions, need for the addition of new questions, and connectivity issues. Although informants reported monitoring helped organizations identify gaps during the response, the scarcity and inconsistency of the reported data make it difficult to draw any conclusions about program effectiveness, accountability in humanitarian response, or to make recommendations for improving programming. To improve monitoring, we recommend refining data collection by increasing the quantity of data reported, data consistency, and data relevancy. HIGHLIGHTS Monitoring helped reduce response gaps and improve coverage by allowing organizations to adjust implementation strategies and coordinate with other TWiG members.; Unclear and undefined data collection processes and ambiguous questions in the monitoring forms led to inconsistent data collection.; The scarcity and inconsistency of the reported data made it difficult to draw any conclusions about program effectiveness and accountability.;
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- 2021
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26. Eocene-Oligocene southwest Pacific Ocean paleoceanography new insights from foraminifera chemistry (DSDP site 277, Campbell Plateau)
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F. Hodel, C. Fériot, G. Dera, M. De Rafélis, C. Lezin, E. Nardin, D. Rouby, M. Aretz, P. Antonio, M. Buatier, M. Steinmann, F. Lacan, C. Jeandel, and V. Chavagnac
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paleoceanography ,climate ,foraminifera ,Eocene ,Oligocene ,southwest Pacific Ocean ,Science - Abstract
Despite its major role in the Earth’s climate regulation, the evolution of high-latitude ocean dynamics through geological time remains unclear. Around Antarctica, changes in the Southern Ocean (SO) circulation are inferred to be responsible for cooling from the late Eocene and glaciation in the early Oligocene. Here, we present a geochemical study of foraminifera from DSDP Site 277 (Campbell Plateau), to better constrain thermal and redox evolution of the high latitude southwest Pacific Ocean during this time interval. From 56 to 48 Ma, Mg/Ca- and δ18O-paleothermometers indicate high surface and bottom water temperatures (24–26°C and 12–14°C, respectively), while weak negative Ce anomalies indicate poorly oxygenated bottom waters. This is followed by a cooling of ∼4° between 48 and 42 Ma, possibly resulting from a weakening of a proto-EAC (East Australian Current) and concomitant strengthening of a proto-Ross gyre. This paleoceanographic change is associated with better ventilation at Site 277, recorded by an increasing negative Ce anomaly. Once this proto-Ross gyre was fully active, increasing biogenic sedimentation rates and decreasing Subbotina sp. δ13C values indicate enhanced productivity. This resulted in a shoaling of the oxygen penetration in the sediment pile recorded by increasing the foraminiferal U/Ca ratio. The negative Ce anomaly sharply increased two times at ∼35 and ∼31 Ma, indicating enhanced seawater ventilation synchronously with the opening of the Tasmanian and Drake Passage gateways, respectively. The Oligocene glaciation is recorded by a major increase of bottom seawater δ18O during the EOT (Eocene-Oligocene Transition) while Mg/Ca-temperatures remain rather constant. This indicates a significant ice control on the δ18O record.
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- 2022
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27. Enhanced Recursive Reed-Muller Erasure Decoding
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Soro, Alexandre, Lacan, Jerome, Roca, Vincent, Savin, Valentin, and Cunche, Mathieu
- Subjects
Computer Science - Information Theory - Abstract
Recent work have shown that Reed-Muller (RM) codes achieve the erasure channel capacity. However, this performance is obtained with maximum-likelihood decoding which can be costly for practical applications. In this paper, we propose an encoding/decoding scheme for Reed-Muller codes on the packet erasure channel based on Plotkin construction. We present several improvements over the generic decoding. They allow, for a light cost, to compete with maximum-likelihood decoding performance, especially on high-rate codes, while significantly outperforming it in terms of speed.
- Published
- 2016
28. Estimation of Timing Offsets and Phase Shifts Between Packet Replicas in MARSALA Random Access
- Author
-
Zidane, Karine, Lacan, Jérome, Gineste, Mathieu, Bes, Caroline, Deramecourt, Arnaud, and Dervin, Mathieu
- Subjects
Computer Science - Information Theory - Abstract
Multi-replicA decoding using corRelation baSed LocALisAtion (MARSALA) is a recent random access technique designed for satellite return links. It follows the multiple transmission and interference cancellation scheme of Contention Resolution Diversity Slotted Aloha (CRDSA). In addition, at the receiver side, MARSALA uses autocorrelation to localise replicas of a same packet so as to coherently combine them. Previous work has shown good performance of MARSALA with an assumption of ideal channel state information and perfectly coherent combining of the different replicas of a given packet. However, in a real system, synchronisation errors such as timing offsets and phase shifts between the replicas on separate timeslots will result in less constructive combining of the received signals. This paper describes a method to estimate and compensate the timing and phase differences between the replicas, prior to their combination. Then, the impact of signal misalignment in terms of residual timing offsets and phase shifts, is modeled and evaluated analytically. Finally, the performance of MARSALA in realistic channel conditions is assessed through simulations, and compared to CRDSA in various scenarios.
- Published
- 2015
29. Conclusion: Situating multispecies relations in Southern Africa in their local historical and political contexts
- Author
-
Vehrs, Hauke-Peter, Lacan, Léa, and Bollig, Michael
- Published
- 2024
- Full Text
- View/download PDF
30. Killing tsetse and/or saving wildlife? A multispecies assemblage in colonial Zambia (1895–1959)
- Author
-
Lacan, Léa
- Abstract
This article investigates the problem of the tsetse fly and the trypanosomiasis disease it conveys as a transforming multispecies assemblage in colonial Zambia from the late nineteenth century until 1959. Based on archival research, it analyses the tsetse fly (Glossina morsitans) as a moving target; not only a mobile and elusive insect but also a moving field of knowledge bringing multiple stakeholders into dialogue. It shows that tsetse control and wildlife conservation emerged together in colonial Zambia, in conflicting but also synergising ways, and that the association of large mammals to G. morsitanslaid the ground for their classification as killable or preservable species. In the crossed influence of diverse regional colonial expertise, the article finds that the complex multispecies relations between the tsetse fly, the trypanosomes, wildlife, vegetation, humans and cattle, mediated and enacted by colonial experts and others, shaped institutions, policies and landscapes.
- Published
- 2024
- Full Text
- View/download PDF
31. Introduction: Multispecies encounters in conservation landscapes in Southern Africa
- Author
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Lacan, Léa, Vehrs, Hauke-Peter, and Bollig, Michael
- Published
- 2024
- Full Text
- View/download PDF
32. Enhanced HARQ for Delay Tolerant Services in Mobile Satellite Communications
- Author
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Ahmad, Rami Ali, Lacan, Jérôme, Arnal, Fabrice, Gineste, Mathieu, and Clarac, Laurence
- Subjects
Computer Science - Information Theory ,Computer Science - Networking and Internet Architecture - Abstract
The objective of our paper is to improve efficiency (in terms of throughput or system capacity) for mobile satellite communications. In this context, we propose an enhanced Hybrid Automatic Repeat reQuest (HARQ) for delay tolerant services. Our proposal uses the estimation of the mutual information. We evaluate the performance of the proposed method for a land mobile satellite channel by means of simulations. Results are compared with those obtained with a classical incremental redundancy (IR) HARQ scheme. The technique we propose, shows a better performance in terms of efficiency while maintaining an acceptable delay for services., Comment: 6 pages, 5 figures, The Seventh International Conference on Advances in Satellite and Space Communications SPACOMM 2015. arXiv admin note: substantial text overlap with arXiv:1411.3625
- Published
- 2015
33. Enhancing Satellite System Throughput Using Adaptive HARQ for Delay Tolerant Services in Mobile Communications
- Author
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Ahmad, Rami Ali, Lacan, Jérôme, Arnal, Fabrice, Gineste, Mathieu, and Clarac, Laurence
- Subjects
Computer Science - Networking and Internet Architecture - Abstract
In this paper we propose the introduction of adaptive hybrid automatic repeat request (HARQ) in the context of mobile satellite communications. HARQ schemes which are commonly used in terrestrial links, can be adapted to improve the throughput for delay tolerant services. The proposed method uses the estimation of the mutual information between the received and the sent symbols, in order to estimate the number of bits necessary to decode the message at next transmission. We evaluate the performance of our method by simulating a land mobile satellite (LMS) channel. We compare our results with the static HARQ scheme, showing that our adaptive retransmission technique has better efficiency while keeping an acceptable delay for services., Comment: 7 pages, 8 figures, Wireless Telecommunications Symposium WTS 2015
- Published
- 2014
34. Promoting oil palm-based agroforestry systems: an asset for the sustainability of the sector
- Author
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Masure Alix, Martin Pierre, Lacan Xavier, and Rafflegeau Sylvain
- Subjects
oil palm ,agroforestry ,agroecosystem ,diversification ,resilience ,Agriculture (General) ,S1-972 ,Plant culture ,SB1-1110 - Abstract
Until recently, the massive development of industrial and smallholder oil palm (Elaeis guineensis Jacq.) plantations has generally been conducted according to the monocrop model. However, alternative cropping systems have emerged, based on more diversified systems that combine various crops within the oil palm plots. By giving this plant a status equivalent to that of a tree, these practices correspond to agroforestry systems. In the present study, 39 agroforestry systems were identified worldwide through a preliminary literature review, a review of NGO websites and expert surveys. Our results reveal five different types of oil palm agroforestry systems: (i) associations with livestock during the production phase of the oil palm; (ii) traditional African palm and food crop systems sustained over time; (iii) associations with food crops during the juvenile phase of the oil palm; (iv) systems developed by family farms that permanently associate other plants; and (v) prototype designs developed by research institutions, often at the request of local agricultural enterprises. The spatiotemporal description of these systems enabled us to identify associated ecosystem services. Building on various proposals of biodiversity insertion in a monoculture to convert it into an agroforestry system, the present study offers new perspectives for the sustainable development of palm oil production.
- Published
- 2023
- Full Text
- View/download PDF
35. Quasi-optimal grouping for broadcast systems with hierarchical modulation
- Author
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Meric, Hugo, Piquer, José, and Lacan, Jérôme
- Subjects
Computer Science - Networking and Internet Architecture ,Computer Science - Information Theory - Abstract
Recently, we proposed to combine time sharing with hierarchical modulation to increase the transmission rate of broadcast systems. Our proposal involves to group the receivers in pairs in order to transmit with hierarchical modulation. We introduced several grouping strategies but the optimal matching remained an open question. In this letter, we show that the optimal grouping is the solution of an assignment problem, for which efficient algorithms exist such as the Hungarian method. Based on this algorithm, we study the performance of the optimal grouping in terms of spectrum efficiency for a DVB-S2 system., Comment: Submitted
- Published
- 2014
36. Improved channel estimation for interference cancellation in random access methods for satellite communications
- Author
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Zidane, Karine, Lacan, Jérôme, Boucheret, Marie-Laure, and Poulliat, Charly
- Subjects
Computer Science - Information Theory - Abstract
In the context of satellite communications, random access (RA) methods can significantly increase throughput and reduce latency over the network. The recent RA methods are based on multi-user multiple access transmission at the same time and frequency combined with interference cancellation and iterative decoding at the receiver. Generally, it is assumed that perfect knowledge of the interference is available at the receiver. In practice, the interference term has to be accurately estimated to avoid performance degradation. Several estimation techniques have been proposed lately in the case of superimposed signals. In this paper, we present an improved channel estimation technique that combines estimation using an autocorrelation based method and the Expectation-Maximization algorithm, and uses Pilot Symbol Assisted Modulation to further improve the performance and achieve optimal interference cancellation., Comment: submitted to ASMS 2014
- Published
- 2014
37. Dissolved iron in the North Atlantic Ocean and Labrador Sea along the GEOVIDE section (GEOTRACES section GA01)
- Author
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M. Tonnard, H. Planquette, A. R. Bowie, P. van der Merwe, M. Gallinari, F. Desprez de Gésincourt, Y. Germain, A. Gourain, M. Benetti, G. Reverdin, P. Tréguer, J. Boutorh, M. Cheize, F. Lacan, J.-L. Menzel Barraqueta, L. Pereira-Contreira, R. Shelley, P. Lherminier, and G. Sarthou
- Subjects
Ecology ,QH540-549.5 ,Life ,QH501-531 ,Geology ,QE1-996.5 - Abstract
Dissolved Fe (DFe) samples from the GEOVIDE voyage (GEOTRACES GA01, May–June 2014) in the North Atlantic Ocean were analyzed using a seaFAST-pico™ coupled to an Element XR sector field inductively coupled plasma mass spectrometer (SF-ICP-MS) and provided interesting insights into the Fe sources in this area. Overall, DFe concentrations ranged from 0.09±0.01 to 7.8±0.5 nmol L−1. Elevated DFe concentrations were observed above the Iberian, Greenland, and Newfoundland margins likely due to riverine inputs from the Tagus River, meteoric water inputs, and sedimentary inputs. Deep winter convection occurring the previous winter provided iron-to-nitrate ratios sufficient to sustain phytoplankton growth and lead to relatively elevated DFe concentrations within subsurface waters of the Irminger Sea. Increasing DFe concentrations along the flow path of the Labrador Sea Water were attributed to sedimentary inputs from the Newfoundland Margin. Bottom waters from the Irminger Sea displayed high DFe concentrations likely due to the dissolution of Fe-rich particles in the Denmark Strait Overflow Water and the Polar Intermediate Water. Finally, the nepheloid layers located in the different basins and at the Iberian Margin were found to act as either a source or a sink of DFe depending on the nature of particles, with organic particles likely releasing DFe and Mn particle scavenging DFe.
- Published
- 2020
- Full Text
- View/download PDF
38. Functional properties and potential application of ethanol tolerant β-glucosidases from Pichia ofunaensis and Trichosporon multisporum yeasts
- Author
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Vaz, Jaqueline Elaine, Rabelo, Lacan, Zaiter, Mohammed Anas, Pereira, Waldir Eduardo Simioni, Metzker, Gustavo, Boscolo, Maurício, da Silva, Roberto, Gomes, Eleni, and da Silva, Ronivaldo Rodrigues
- Published
- 2021
- Full Text
- View/download PDF
39. VIRAL: coupling congestion control with fair video quality metric
- Author
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Thai, Tuan Tran, Lochin, Emmanuel, and Lacan, Jérôme
- Published
- 2020
- Full Text
- View/download PDF
40. Joint On-the-Fly Network Coding/Video Quality Adaptation for Real-Time Delivery
- Author
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Thai, Tuan Tran, Lacan, Jérôme, and Lochin, Emmanuel
- Subjects
Computer Science - Multimedia - Abstract
This paper introduces a redundancy adaptation algorithm for an on-the-fly erasure network coding scheme called Tetrys in the context of real-time video transmission. The algorithm exploits the relationship between the redundancy ratio used by Tetrys and the gain or loss in encoding bit rate from changing a video quality parameter called the Quantization Parameter (QP). Our evaluations show that with equal or less bandwidth occupation, the video protected by Tetrys with redundancy adaptation algorithm obtains a PSNR gain up to or more 4 dB compared to the video without Tetrys protection. We demonstrate that the Tetrys redundancy adaptation algorithm performs well with the variations of both loss pattern and delay induced by the networks. We also show that Tetrys with the redundancy adaptation algorithm outperforms FEC with and without redundancy adaptation.
- Published
- 2013
41. On the Trade-off Between Spectrum Efficiency with Dedicated Access and Short End-to-End Transmission Delays with Random Access in DVB-RCS2
- Author
-
Kuhn, Nicolas, Bui, Huyen-Chi, Lacan, Jerome, Radzik, Jose, and Lochin, Emmanuel
- Subjects
Computer Science - Networking and Internet Architecture - Abstract
This paper analyses the performance of TCP over random and dedicated access methods in the context of DVB-RCS2. Random access methods introduce a lower connection delay compared to dedicated methods. We investigate the poten- tial to improve the performance of short flows in regards to transmission delay, over random access methods for DVB- RCS2 that is currently under development. Our simulation experiments show that the transmission of the first ten IP datagrams of each TCP flow can be 500 ms faster with ran- dom access than with dedicated access making the former of interest to carry Internet traffic. Such methods, however, are less efficient in regards to bandwidth usage than dedicated access mecanisms and less reliable in overloaded network conditions. Two aspects of channel usage optimization can be distinguished: reducing the duration of ressource utiliza- tion with random access methods, or increasing the spec- trum efficiency with dedicated access methods. This article argues that service providers may let low-cost users exploit the DVB-RCS2 to browse the web by introducing different services, which choice is based on the channel access method., Comment: ACMLCDNet 2013
- Published
- 2013
42. Physical Channel Access (PCA): Time and Frequency Access Methods Emulation in NS-2
- Author
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Kuhn, Nicolas, Mehani, Olivier, Bui, Huyen-Chi, Lacan, Jerome, Radzik, Jose, and Lochin, Emmanuel
- Subjects
Computer Science - Networking and Internet Architecture - Abstract
We present an NS-2 module, Physical Channel Access (PCA), to simulate different access methods on a link shared with Multi-Frequency Time Division Multiple Access (MF-TDMA). This tech- nique is widely used in various network technologies, such as satellite communication. In this context, different access methods at the gateway induce different queuing delays and available capacities, which strongly impact transport layer performance. Depending on QoS requirements, design of new congestion and flow control mechanisms and/or access methods requires evaluation through simulations. PCA module emulates the delays that packets will experience using the shared link, based on descriptive parameters of lower layers characteris- tics. Though PCA has been developed with DVB-RCS2 considerations in mind (for which we present a use case), other MF-TDMA-based appli- cations can easily be simulated by adapting input parameters. Moreover, the presented implementation details highlight the main methods that might need modifications to implement more specific functionality or emulate other similar access methods (e.g., OFDMA).
- Published
- 2013
43. Interferences and Matrix Effects on Iron Isotopic Composition Measurements by 57Fe-58Fe Double-Spike Multi-Collector Inductively Coupled Plasma Mass Spectrometry; the Importance of Calcium and Aluminum Interferences
- Author
-
F. Lacan, L. Artigue, J. K. Klar, C. Pradoux, J. Chmeleff, and R. Freydier
- Subjects
iron isotopes ,MC-ICPMS ,double-spike ,interferences ,matrix effects ,calcium ,Environmental technology. Sanitary engineering ,TD1-1066 - Abstract
Multi-collector inductively coupled plasma mass spectrometers (MC-ICPMS) are widely used for Fe isotope measurements. The latter may be perturbed by interferences (notably from Cr and Ni) and matrix effects (notably from major elements), caused by elements remaining in the samples after purification. We quantified some of these perturbations and our ability to correct them whenever possible, using Thermo Neptune and Neptune Plus MC-ICPMS with a 57-58Fe double-spike mass bias correction. 54Cr and 58Ni isobaric interference corrections were found to be extremely efficient up to Cr/Fe=0.12 and Ni/Fe=0.04 (g/g natural Fe). Matrix effects were found negligible up to at least Na/Fe=175, Mg/Fe=10, K/Fe=1.5, and Mo/Fe=75 (g/g natural Fe). 28Si2+ interference was found negligible up to Si/Fe=50. Finally, we found that calcium and aluminum could cause significant interferences (e.g., 40Ca16O and 27Al2+), for Ca/Fe ≥ 2.5 and Al/Fe ≥ 2.5. The perturbation intensity relative to the Ca/Fe ratio was found dependent on the measurement conditions (plateau width). While working with samples with potentially high calcium or aluminum contents (such as calcite minerals or tests, bones and teeth, or marine samples and crustal rocks), we recommend to carefully take into account Ca and Al while tuning the instrument and checking the measurement accuracy with isotopic standards (i.e., doping the isotopic standard with Ca and Al levels comparable to those of the samples).
- Published
- 2021
- Full Text
- View/download PDF
44. CAR-NK Cells: A Chimeric Hope or a Promising Therapy?
- Author
-
Mohamad Sabbah, Ludovic Jondreville, Claire Lacan, Francoise Norol, Vincent Vieillard, Damien Roos-Weil, and Stéphanie Nguyen
- Subjects
natural killer cells ,CAR-NK ,immunotherapy ,leukemia ,lymphoma ,allogenic CAR ,Neoplasms. Tumors. Oncology. Including cancer and carcinogens ,RC254-282 - Abstract
Immunotherapy with chimeric antigen receptor-engineered T cells (CAR-T) has revolutionized the treatment landscape of relapsed/refractory B-cell malignancies. Nonetheless, the use of autologous T cells has certain limitations, including the variable quality and quantity of collected effector T cells, extended time of cell processing, limited number of available CAR cells, toxicities, and a high cost. Thanks to their powerful cytotoxic capabilities, with proven antitumor effects in both haploidentical hematopoietic stem cell transplantation and adoptive cell therapy against solid tumors and hematological malignancies, Natural Killer cells could be a promising alternative. Different sources of NK cells can be used, including cellular lines, cord blood, peripheral blood, and induced pluripotent stem cells. Their biggest advantage is the possibility of using them in an allogeneic context without major toxic side effects. However, the majority of the reports on CAR-NK cells concern preclinical or early clinical trials. Indeed, NK cells might be more difficult to engineer, and the optimization and standardization of expansion and transfection protocols need to be defined. Furthermore, their short persistence after infusion is also a major setback. However, with recent advances in manufacturing engineered CAR-NK cells exploiting their cytolytic capacities, antibody-dependent cellular cytotoxicity (ADCC), and cytokine production, “off-the-shelf” allogeneic CAR-NK cells can provide a great potential in cancer treatments.
- Published
- 2022
- Full Text
- View/download PDF
45. Enabling Blockchain Services for IoE with Zk-Rollups
- Author
-
Thomas Lavaur, Jérôme Lacan, and Caroline P. C. Chanel
- Subjects
IoT ,IoE ,blockchain ,rollup ,Zero-Knowledge ,zk-rollup ,Chemical technology ,TP1-1185 - Abstract
The Internet of Things includes all connected objects from small embedded systems with low computational power and storage capacities to efficient ones, as well as moving objects like drones and autonomous vehicles. The concept of Internet of Everything expands upon this idea by adding people, data and processing. The adoption of such systems is exploding and becoming ever more significant, bringing with it questions related to the security and the privacy of these objects. A natural solution to data integrity, confidentiality and single point of failure vulnerability is the use of blockchains. Blockchains can be used as an immutable data layer for storing information, avoiding single point of failure vulnerability via decentralization and providing strong security and cryptographic tools for IoE. However, the adoption of blockchain technology in such heterogeneous systems containing light devices presents several challenges and practical issues that need to be overcome. Indeed, most of the solutions proposed to adapt blockchains to devices with low resources confront difficulty in maintaining decentralization or security. The most interesting are probably the Layer 2 solutions, which build offchain systems strongly connected to the blockchain. Among these, zk-rollup is a promising new generation of Layer 2/off-chain schemes that can remove the last obstacles to blockchain adoption in IoT, or more generally, in IoE. By increasing the scalability and enabling rule customization while preserving the same security as the Layer 1 blockchain, zk-rollups overcome restrictions on the use of blockchains for IoE. Despite their promises illustrated by recent systems proposed by startups and private companies, very few scientific publications explaining or applying this barely-known technology have been published, especially for non-financial systems. In this context, the objective of our paper is to fill this gap for IoE systems in two steps. We first propose a synthetic review of recent proposals to improve scalability including onchain (consensus, blockchain organization, …) and offchain (sidechain, rollups) solutions and we demonstrate that zk-rollups are the most promising ones. In a second step, we focus on IoE by describing several interesting features (scalability, dynamicity, data management, …) that are illustrated with various general IoE use cases.
- Published
- 2022
- Full Text
- View/download PDF
46. Chitosan Effect on Hardening Dynamics of Calcium Phosphate Cement: Low-Field NMR Relaxometry Investigations
- Author
-
Ioana Lacan, Mărioara Moldovan, Codruța Sarosi, and Ioan Ardelean
- Subjects
bone cements ,calcium phosphate ,chitosan ,hardening ,NMR relaxometry ,Organic chemistry ,QD241-441 - Abstract
Calcium phosphate cements are used in dentistry and orthopedics to repair and reconstruct bone defects. The properties of these bone cements can be improved by introducing additives into their composition. One favorable additive is chitosan, which can be beneficial but can also cause considerable damage if it has a high load, thus, limiting its clinical applicability and performance. That is why understanding chitosan’s role in cement composition is an important issue when developing new materials. The present work uses low-field nuclear magnetic resonance (NMR) relaxometry to investigate the effect introduced by the addition of chitosan on the hardening process of calcium phosphate cement. Two samples, prepared with and without chitosan, were comparatively investigated during the first six minutes of hardening. The liquid evolution inside these samples was monitored using transverse relaxation time distributions. It demonstrated an acceleration effect on the hardening dynamics introduced by the presence of chitosan. Furthermore, it was shown that even after one hour of hardening, there were still unreacted monomers inside the bone cement and their amount was reduced in the presence of chitosan.
- Published
- 2022
- Full Text
- View/download PDF
47. Erasure Coding and Congestion Control for Interactive Real-Time Communication
- Author
-
Tournoux, Pierre-Ugo, Thai, Tuan Tran, Lochin, Emmanuel, Lacan, Jerome, and Roca, Vincent
- Subjects
Computer Science - Networking and Internet Architecture ,Computer Science - Multimedia - Abstract
The use of real-time applications over the Internet is a challenging problem that the QoS epoch attempted to solve by proposing the DiffServ architecture. Today, the only existing service provided by the Internet is still best-effort. As a result, multimedia applications often perform on top of a transport layer that provides a variable sending rate. In an obvious manner, this variable sending rate is an issue for these applications with strong delay constraint. In a real-time context where retransmission can not be used to ensure reliability, video quality suffers from any packet losses. In this position paper, we discuss this problem and motivate why we want to bring out a certain class of erasure coding scheme inside multimedia congestion control protocols such as TFRC., Comment: IAB/IRTF Workshop on Congestion Control for Interactive Real-Time Communication
- Published
- 2012
48. Multi-slot Coded ALOHA with Irregular Degree Distribution
- Author
-
Bui, Huyen Chi, Lacan, Jérôme, and Boucheret, Marie-Laure
- Subjects
Computer Science - Information Theory - Abstract
This paper proposes an improvement of the random multiple access scheme for satellite communication named Multislot coded ALOHA (MuSCA). MuSCA is a generalization of Contention Resolution Diversity Slotted ALOHA (CRDSA). In this scheme, each user transmits several parts of a single codeword of an error correcting code instead of sending replicas. At the receiver level, the decoder collects all these parts and includes them in the decoding process even if they are interfered. In this paper, we show that a high throughput can be obtained by selecting variable code rates and user degrees according to a probability distribution. With an optimal irregular degree distribution, our system achieves a normalized throughput up to 1.43, resulting in a significant gain compared to CRDSA and MuSCA. The spectral efficiency and the implementation issues of the scheme are also analyzed., Comment: 6 pages, 8 figures
- Published
- 2012
49. CLIFT: a Cross-Layer InFormation Tool to perform cross-layer analysis based on real physical traces
- Author
-
Kuhn, N., Lochin, E., Lacan, J., Boreli, R., Bes, C., and Clarac, L.
- Subjects
Computer Science - Networking and Internet Architecture - Abstract
Considering real physical (MAC/PHY) traces inside network simulations is a complex task that might lead to complex yet approximated models. However, realistic cross-layer analysis with the upper layer and in particular the transport layer cannot be driven without considering the MAC/PHY level. In this paper, we propose to cope with this problem by introducing a software that translates real physical events from a given trace in order to be used inside a network simulator such as $ns$-2. The main objective is to accurately perform analysis of the impact of link layer reliability schemes (obtained by the use of real physical traces) on transport layer performance. We detail the internal mechanisms and the benefits of this software with a focus on 4G satellite communications scenarios and present the resulting metrics provided by CLIFT to perform consistent cross-layer analysis.
- Published
- 2012
50. Enabling Realistic Cross-Layer Analysis based on Satellite Physical Layer Traces
- Author
-
Kuhn, Nicolas, Lochin, Emmanuel, Lacan, Jerome, Boreli, Roksana, Bes, Caroline, and Clarac, Laurence
- Subjects
Computer Science - Networking and Internet Architecture ,68M99 ,C.2.5 ,D.1.1 ,G.1.0 - Abstract
We present a solution to evaluate the performance of transport protocols as a function of link layer reliability schemes (i.e. ARQ, FEC and Hybrid ARQ) applied to satellite physical layer traces. As modelling such traces is complex and may require approximations, the use of real traces will minimise the potential for erroneous performance evaluations resulting from imperfect models. Our Trace Manager Tool (TMT) produces the corresponding link layer output, which is then used within the ns-2 network simulator via the additionally developed ns-2 interface module. We first present the analytical models for the link layer with bursty erasure packets and for the link layer reliability mechanisms with bursty erasures. Then, we present details of the TMT tool and our validation methodology, demonstrating that the selected performance metrics (recovery delay and throughput efficiency) exhibit a good match between the theoretical results and those obtained with TMT. Finally, we present results showing the impact of different link layer reliability mechanisms on the performance of TCP Cubic transport layer protocol., Comment: 6 pages, 5 figures and 1 table. Submitted at PIMRC 2012
- Published
- 2012
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