Mécano-biologie des tissus hétérogènes par changement d'échelles : application à l'ostéosarcome

L’ostéosarcome est une tumeur osseuse primitive qui survient principalement chez les adolescents et les jeunes adultes. Le taux de survie à 5 ans est de 70% et chute à 25% pour les patients présentant des métastases ou ne répondant pas aux traitements. De nouveaux développements sont nécessaires pour améliorer la prise en charge spécifique des patients. Ce type de tumeurs présente de fortes hétérogénéités spatiales dans la micro-architecture osseuse, dans la distribution des populations cellulaires mais aussi dans la réponse au traitement. A l’échelle tissulaire et du point de vue de la biophysique, l’ostéosarcome peut être considéré comme un milieu poreux fortement hétérogène et nous supposons que l’ostéosarcome est sensible aux effets mécaniques lors de sa formation et de son évolution. Nous proposons une méthode de changement d’échelles pour caractériser les propriétés mécaniques de tels milieux poreux. La méthode s’appuie sur une approche séquentielle "grid-block" combinée à une méthode "extend-local". La méthodologie est adaptée à des images de grandes tailles et notamment aux images binaires de coupes histologiques d’ostéosarcomes obtenues en routine clinique. Des modèles d’écoulement, de diffusion, d’élasticité et de poroélasticité sont étudiés. Les paramètres équivalents, constants par morceaux, de type perméabilités tissulaires et coefficients de raideurs tissulaires sont déterminés avec fiabilité. Plusieurs résultats méthodologiques ont été obtenus tels que les inégalités portant sur les paramètres équivalents en fonction des conditions aux limites imposées sur les éléments du "grid-block" ou la caractérisation du rôle des méthodes "extendlocal" dans le calcul des paramètres de raideur. Dans une étude clinique préliminaire, des relations entre les propriétés mécaniques tissulaires et les paramètres cellulaires sont données. Une cohorte réduite de patients montre que la réponse au traitement peut être corrélée à l’architecture du micro-environnement et à ses propriétés mécaniques. Ceci pourrait soutenir la recherche de marqueurs mécanobiologiques pour le suivi de la réponse au traitement chez les patients atteints d’ostéosarcome

Distribution-Level Flexibility Market for Congestion Management

Nowadays, problems facing Distribution System Operators (DSOs) due to demand increase and the wide penetration of renewable energy are usually solved by means of grid reinforcement. However, the smart grid paradigm enables the deployment of demand flexibility for congestion management in distribution grids. This could substitute, or at least postpone, these needed investments. A key role in this scheme is the aggregator, who can act as a "flexibility provider" collecting the available flexibility from the consumers. Under this paradigm, this paper proposes a flexibility market led by the DSO and aimed at solving distribution grid congestions. The proposal also includes a flexibility market clearing algorithm, which is easy to implement, has low computational requirements and considers the energy rebound effect. The proposed design has the advantage of excluding the DSO's need for trading in energy markets. Also, the solution algorithm proposed is fully compatible with already existing grid analysis tools. The proposed electricity market is tested with two case studies from a real Spanish distribution network, where the proposed clearing algorithm is used, and finally, results are presented and discussed

A Decentralized Local Flexibility Market Considering the Uncertainty of Demand

The role of the distribution system operator (DSO) is evolving with the increasing possibilities of demand management and flexibility. Rather than implementing conventional approaches to mitigate network congestions, such as upgrading existing assets, demand flexibility services have been gaining much attention lately as a solution to defer the need for network reinforcements. In this paper, a framework for a decentralized local market that enables flexibility services trading at the distribution level is introduced. This market operates on two timeframes, day-ahead and real-time and it allows the DSO to procure flexibility services which can help in its congestion management process. The contribution of this work lies in considering the uncertainty of demand during the day-ahead period. As a result, we introduce a probabilistic process that supports the DSO in assessing the true need of obtaining flexibility services based on the probability of congestion occurrence in the following day of operation. Besides being able to procure firm flexibility for high probable congestions, a new option is introduced, called the right-to-use option, which enables the DSO to reserve a specific amount of flexibility, to be called upon later if necessary, for congestions that have medium probabilities of taking place. In addition, a real-time market for flexibility trading is presented, which allows the DSO to procure flexibility services for unforeseen congestions with short notice. Also, the effect of the penetration level of flexibility on the DSO's total cost is discussed and assessed. Finally, a case study is carried out for a real distribution network feeder in Spain to illustrate the impact of the proposed flexibility framework on the DSO's congestion management process

From passion to activism? The politics, communications, and creativity of participatory networks in the MENA region

This paper argues that while platforms such as Facebook, YouTube and Twitter are unquestionably allowing some young citizens in the Middle East and North Africa (MENA) region quicker, easier and greater access to job opportunities and likeminded groups and citizens inside and outside the region, class-based digital divides exist, scepticism of new media remains, online surveillance and harassment are rife, and social media fatigue is common. Existing community structures, creativity and emerging media remain important for youth participatory civic networks in Jordan, Morocco, Tunisia and the United Arab Emirates (UAE). Communities, local neighbourhoods, private and public spaces, and commercial media cultures vie for position in young people’s social worlds and civic identities. Young Emiratis, expats, Jordanians, Jordanian Palestinians, Moroccans and Tunisians practice their political values and social relationships in networks that are strongly inflected by social class and gender. Indigeneity, race and sexuality also inflect the cultural histories and practices on which young people in the region draw. Individual charisma, self-exploitation, arts and crafts, old media tools and local friendship or kinship networks are still the basis for much civic solidarity, political trust, critique and creative dissemination in the MENA region. This has profound implications for technologically oriented protest narratives, for discussions of personalisation, and for democracy

Human-robot interaction torque estimation methods for a lower limb rehabilitation robotic system with uncertainties

Lower limb rehabilitation robot (LLRR) users, to successfully conduct isotonic exercises, require real-time feedback on the torque they exert on the robot to meet the goal of the treatment. Still, direct torque measuring is expensive, and indirect encoder-based estimation strategies, such as inverse dynamics (ID) and Nonlinear Disturbance Observers (NDO), are sensitive to Body Segment Inertial Parameters (BSIPs) uncertainties. We envision a way to minimize such parametric uncertainties. This paper proposes two human–robot interaction torque estimation methods: the Identified ID-based method (IID) and the Identified NDO-based method (INDO). Evaluating in simulation the proposal to apply, in each rehabilitation session, a sequential two-phase method: (1) An initial calibration phase will use an online parameter estimation to reduce sensitivity to BSIPs uncertainties. (2) The torque estimation phase uses the estimated parameters to obtain a better result. We conducted simulations under signal-to-noise ratio (SNR) = 40 dB and 20% BSIPs uncertainties. In addition, we compared the effectiveness with two of the best methods reported in the literature via simulation. Both proposed methods obtained the best Coefficient of Correlation, Mean Absolute Error, and Root Mean Squared Error compared to the benchmarks. Moreover, the IID and INDO fulfilled more than 72.2% and 88.9% of the requirements, respectively. In contrast, both methods reported in the literature only accomplish 27.8% and 33.3% of the requirements when using simulations under noise and BSIPs uncertainties. Therefore, this paper extends two methods reported in the literature and copes with BSIPs uncertainties without using additional sensors

Generalization of the coupled dipole method to periodic structures

We present a generalization of the coupled dipole method to the scattering of light by arbitrary periodic structures. This new formulation of the coupled dipole method relies on the same direct-space discretization scheme that is widely used to study the scattering of light by finite objects. Therefore, all the knowledge acquired previously for finite systems can be transposed to the study of periodic structures.Comment: 5 pages, 2 figures, and 1 tabl

Upscaling of fluid flow in spatially heterogeneous bone tumors

Osteosarcoma is a malignant bone tumor that preferentially arises in adolescents and young adults. Like many sarcomas with complex genomics, this type of tumors exhibits strong spatial heterogeneities in terms of micro-architecture or differentiated response to treatments due to localized effect of chemotherapy. Clinical images at a tissue scale such as histological and immunohistological sections, exhibit three phases: fluid, solid, cells populations. Therefore the tumor can be considered as a porous medium. The objective of this work was to develop a mechanical approach based on upscaling methods to study the interstitial flow within the tumor at the tissue scale. The statistical study of the micro-architecture of the media shows that the identification of characteristic lengths is complex and that a separation of spatial scales is not necessarily identified. We therefore chose a special sequential upscaling technique, named Grid-Block approach to solve this problem

Fruit and Vegetable Consumption and Potential Moderators Associated with All-Cause Mortality in a Representative Sample of Spanish Older Adults

This study sought to determine the association between levels of fruit and vegetable consumption and time to death, and to explore potential moderators. We analyzed a nationally-representative sample of 1699 older adults aged 65+ who were followed up for a period of 6 years. Participants were classified into low (≤3 servings day), medium (4), or high (≥5) consumption using tertiles. Unadjusted and adjusted cox proportional hazard regression models (by age, gender, cohabiting, education, multimorbidity, smoking, physical activity, alcohol consumption, and obesity) were calculated. The majority of participants (65.7%) did not meet the recommendation of five servings per day. High fruit and vegetable intake increased by 27% the probability of surviving among older adults with two chronic conditions, compared to those who consumed ≤3 servings per day (HR = 0.38, 95%CI = 0.21-0.69). However, this beneficial effect was not found for people with none, one chronic condition or three or more, indicating that this protective effect might not be sufficient for more severe cases of multimorbidity. Given a common co-occurrence of two non-communicable diseases in the elderly and the low frequency of fruit and vegetable consumption in this population, interventions to promote consuming five or more servings per day could have a significant positive impact on reducing mortality

Immunological and Metabolomic Impacts of Administration of Cry1Ab Protein and MON 810 Maize in Mouse

We have investigated the immunological and metabolomic impacts of Cry1Ab administration to mice, either as a purified protein or as the Cry1Ab-expressing genetically modified (GM) MON810 maize. Humoral and cellular specific immune responses induced in BALB/cJ mice after intra-gastric (i.g.) or intra-peritoneal (i.p.) administration of purified Cry1Ab were analyzed and compared with those induced by proteins of various immunogenic and allergic potencies. Possible unintended effects of the genetic modification on the pattern of expression of maize natural allergens were studied using IgE-immunoblot and sera from maize-allergic patients. Mice were experimentally sensitized (i.g. or i.p. route) with protein extracts from GM or non-GM maize, and then anti-maize proteins and anti-Cry1Ab–induced immune responses were analyzed. In parallel, longitudinal metabolomic studies were performed on the urine of mice treated via the i.g. route. Weak immune responses were observed after i.g. administration of the different proteins. Using the i.p. route, a clear Th2 response was observed with the known allergenic proteins, whereas a mixed Th1/Th2 immune response was observed with immunogenic protein not known to be allergenic and with Cry1Ab. This then reflects protein immunogenicity in the BALB/c Th2-biased mouse strain rather than allergenicity. No difference in natural maize allergen profiles was evidenced between MON810 and its non-GM comparator. Immune responses against maize proteins were quantitatively equivalent in mice treated with MON810 vs the non-GM counterpart and no anti-Cry1Ab–specific immune response was detected in mice that received MON810. Metabolomic studies showed a slight “cultivar” effect, which represented less than 1% of the initial metabolic information. Our results confirm the immunogenicity of purified Cry1Ab without evidence of allergenic potential. Immunological and metabolomic studies revealed slight differences in mouse metabolic profiles after i.g. administration of MON810 vs its non-GM counterpart, but no significant unintended effect of the genetic modification on immune responses was seen