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In axial compressors, shrouded stator cavity flows are responsible for performance degradation due to their interaction with the power stream. The present paper aims at exploring the possibility of employing a single stage high pressure axial compressor as a test vehicle for cavity flows investigations. In a first step, the robustness of the adopted RANS approach is tested against experimental data on the closed-cavity baseline configuration (i.e. no downstream-to-upstream recirculation). In a second phase, the effect of different hub cavities layouts of different levels of realism is numerically investigated. The focus is set on the representativeness of a closed cavity configuration with injection. The cavity flow topology and impact on the overall performance are considered in the analysis. At its final extent, this paper provides numerical and experimental guidelines for the robust assessment of cavity flows topology and performance effects.

International audience; Plus de cinquante millions de personnes vivent avec une épilepsie (PVE) dans le monde, dont 80 % résident dans les pays à revenu faible ou intermédiaire : cette prise de conscience a-t-elle permis une amélioration de la prise en charge de la maladie dans ces pays de la zone tropicale ? Les trois déterminants (socle minimum pour la prise en charge de l’épilepsie) sont bien connus et ont été étudiés : les connaissances sur la maladie et son traitement dans la population générale et chez les PVE, la formation des personnels de santé, et la disponibilité des traitements. Les premières initiatives visant l’amélioration de la prise en charge datent du début des années 1990, et se sont intensifiées durant la décennie 2000. Malgré cela, le déficit de traitement (proportion de PVE qui ne reçoit pas un traitement adéquat) restait élevé. Depuis 2010, l’organisation mondiale de la santé (OMS) et d’autres organismes non-gouvernementaux ont expérimenté des stratégies d’interventions (en agissant sur les 3 déterminants, avec parfois des actions innovantes supplémentaires). Au Mozambique, le taux de prise en charge de l’épilepsie est ainsi passé de 5 à 58 % en 3 ans. Au Myanmar, elle est passée de 2 à 40 % en 3 ans. Au Ghana, la proportion de la population cible en contact avec les services de santé est passée de 14,5 à 38,3 % en 5 ans. Au Vietnam, le déficit de traitement est passé de 58,6 à 39,2 % en 3 ans ; en Chine, de 62,6 % à 49,8 % en 2 ans ; et au Cambodge de 100 à 65,1 % en 1 an. Ces résultats, s’ils sont jugés satisfaisants, servent ensuite d’argumentaires à l’attention des autorités de santé publique pour les généraliser à l’échelle nationale. Cette revue des initiatives et stratégies d’intervention expérimentées récemment a permis une synthèse identifiant des modalités d’interventions efficaces pour ces pays où la démographie médicale, la disponibilité des médicaments antiépileptiques, et les contextes économique et socioculturel composent une équation difficile à résoudre pour la prise en charge de l’épilepsie.

Background The History of African neurology is not well known. Objective Through this communication, our objective is to shed light on this barely History of African Neurology, which is very exciting, rich and rapidly evolving. Its rapid evolution, over the last fifty years is the result of the evolvement of its youth and its training schools. Patients and Methods / Material and Methods At the very beginning, it was confused with the History of Tropical Neurology, until the awareness, around 1950th, by the first neurologists, true pioneers, who worked in sub-Saharan Africa, that cultural and environmental factors conferred genuine specificity to African neurology. Results Since that time, African neurosciences has been structured and developed, contributing to the birth of Neurological Societies in some African countries, then the Pan African Association of Neurological Sciences (PAANS), continental structure, which was the first major cluster of neurologists and neurosurgeons on the continent. In August 2015, the African Academy of Neurology (AfAN) was set up in Dakar, with the aim of bringing together African Neurologists. This Academy, which was created thanks to the joint will of new pioneers and the World Federation of Neurology (WFN), allowed the recognition of neurology in the African continent, alongside other great regional Academies around the world. Conclusion African neurosciences have emerged from the shadows, allowing, in particular, a deepening of the knowledge in neuroepidemiology and the role of socio-economic, ethnographic and cultural factors.

International audience

Pdf of the article is in open access : https://www.osapublishing.org/boe/abstract.cfm?uri=boe-8-10-4568; International audience; This work focuses on the optical stimulation of dorsal root ganglion (DRG) neurons through infrared laser light stimulation. We show that a few millisecond laser pulse at 1875 nm induces a membrane depolarization, which was observed by the patch-clamp technique. This stimulation led to action potentials firing on a minority of neurons beyond an energy threshold. A depolarization without action potential was observed for the majority of DRG neurons, even beyond the action potential energy threshold. The use of ruthenium red, a thermal channel blocker, stops the action potential generation, but has no effects on membrane depolarization. Local temperature measurements reveal that the depolarization amplitude is sensitive to the amplitude of the temperature rise as well as to the time rate of change of temperature, but in a way which may not fully follow a photothermal capacitive mechanism, suggesting that more complex mechanisms are involved.

Epilepsy is felt to be a stigmatizing condition. Stigma has been considered one of the major factors contributing to the burden of epilepsy and to the treatment gap. Stigma has a negative effect on the management of people with epilepsy (PWE). Furthermore, lack of information and inappropriate beliefs are still the factors that most contribute to stigma and discrimination. In this study, we assessed the level of perceived stigma in urban and rural areas and we report their association with in antiepileptic drug (AED) use, effects on seeking medical care, and stigma-associated factors., A cross-sectional study in urban and rural areas in Ecuador from January 2015 until May 2016. People with a confirmed diagnosis of epilepsy were included using three sources of information. The survey was implemented through a questionnaire to determine perceived stigma and evaluate the factors associated. The perceived stigma was measured using the revised Jacoby's stigma scale to detect differences in levels of stigmatization. Access to treatment was evaluated through self-report of AED use, and attainment of medical care and stigma-associated factors were assessed. Furthermore, a multivariate analysis adjusted for possible confounders was performed using stigma as the outcome variable., A total of 243 PWE were interviewed, 65.8% reported feeling stigmatized and 39.1% reported a high stigmatized level. We found a significant difference in high stigma perception in the urban area compared to the rural area. However, the lack of use of AEDs was significantly higher in the rural areas. No significant correlation was found between use of AEDs and the levels of perceived stigma. PWE who did not talk about their condition and those who did not feel well informed about their epilepsy had significantly higher perceived stigma levels. Additionally, the multivariate analysis demonstrated that area, educational level, type of seizure, talk about epilepsy, and information were associated with perceived stigma., The stigma perception was relevant in all PWE. We found a higher stigma level perception in the urban compared to rural area. Moreover, the lack of treatment was a serious problem mainly in rural areas. Even though we did not find that perceived stigma was associated with AED use, our study pointed out the influence of educational level and information related to stigmatization. Consequently, a coordinated effort to reduce stigma should include strategies focused on PWE education and information about their condition.

International audience

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International audience; PURPOSE: Identify epilepsy-associated factors and calculate measures of impact, stigma, quality of life (QOL), knowledge-attitude-practice (KAP) and treatment gap in Prey Veng, Cambodia. METHODS: This first Cambodian population-based case-control study had 96 epileptologist-confirmed epilepsy cases and 192 randomly selected matched healthy controls. Standard questionnaires, which have been used in similar settings, were used for collecting data on various parameters. Univariate and multivariate regression was done to determine odds ratios. Jacoby stigma, 31-item QOL, KAP etc were determined and so were the factors associated with them using STATA software. Treatment gap was measured using direct method. KEY FINDINGS: Multivariate analyses yielded family history of epilepsy, difficult or long delivery, other problems beside seizures (mainly mental retardation, hyperthermia), and eventful pregnancy of the subject's mother as factors associated with epilepsy. There was high frequency of seizure precipitants esp. those related to sleep. Population attributable risk (%) was: family history (15.0), eventful pregnancy of subject's mother (14.5), long/difficult birth (6.5), and other problem beside seizures (20.0). Mean stigma (1.9±1.1, on a scale of 3) was mainly related to treatment efficacy. Mean QOL (5.0±1.4 on a scale of 10) was mainly related to treatment regularity. Cause or risk factor could be determined in 56% of cases. Treatment gap was 65.8%. SIGNIFICANCE: Factors in pre- and perinatal period were found to be most crucial for epilepsy risk in Cambodia which inturn provides major prevention opportunities. A global action plan for treatment, stigma reduction and improvement of QOL should be set-up in this country.

International audience; he appropriation process of the environmental space parameters by elders can be done through the use of color codes that are meaningful to the persons with loss of autonomy. This approach is based upon the natural interpretation of communicating signs and signals by the brain that helps to answer more quickly to critical situation at different degrees. We illustrate first with the transposition of the color codes used in the automobile domain to the housing environment. By extension, we show that intelligent furniture can be designed through ICT and home automation to assist persons with cognitive troubles or motor disability. Finally, we describe the application done in a dare care center for persons with cognitive troubles. Colors of the rooms have been chosen to allow the patients to naturally identify the role of each room.

International audience; The study of laser-neuron interaction has gained interest over the last few years not only for understanding of fundamental mechanisms but also for medical applications such as prosthesis because of the non-invasive characteristic of the laser stimulation. Several authors have shown that near infrared lasers are able to stimulate neurons. It is suggested that a thermal gradient induced by the absorption of the laser radiation on cells is the primary effect but the exact mechanism remains unclear. We show in this work that infrared laser radiations provide a possible way for stimulating retinal and vestibular ganglion cells. We describe relevant physical characteristics allowing safe and reproducible neuron stimulations by single infrared pulses. Calcium fluorescence imaging and electrophysiological recordings have been used to measure ionic exchanges at the neuron membrane. The stimulation system is based on a pulsed laser diode beam of a few mW. Effects of three different wavelengths (from 1470 to 1875 nm) and stimulation durations have been investigated. Variations of the stimulation energy thresholds suggest that the main physical parameter is the water optical absorption. Measurements of the temperature at the cell membrane show that a constant temperature rise is required to stimulate neurons, suggesting a photothermal process.

International audience; Ces travaux s'inscrivent dans le cadre plus général de la réalisation d'une prothèse visuelle destinée aux personnes atteintes de cécité tardive due par exemple à une maladie dégénérative de la rétine comme la rétinite pigmentaire. Les études consacrées au contenu informationnel de la vision prothétique proposent en général une diminution de la résolution des images issues d'une camera. En contraste à cela, nous proposons une approche fonctionnelle originale de la vision prothétique spécifique aux besoins en mobilité, conçue en collaboration avec des rééducateurs spécialisés. Nous proposons de montrer le fort intérêt que représente l'utilisation d'informations 3D de la scène observée. Pour évaluer nos propositions, un dispositif de simulation de vision prothétique a été développé et les résultats des premiers tests effectués apportent des preuves de la pertinence des représentations de l'environnement fournies. Mots-clefs: prothèse visuelle; mobilité; interface homme-machine; simulation de vision prothétique; approche fonctionnelle ; informations 3D.

To face the problems of elderly and disabled people in a rural environment, the district of Guéret (department of Creuse, France) has set up the "Home automation and Health Pole". In association with the University of Limoges, this structure is based on the use of e-technologies together with home automation techniques. In this frame, many international collaborations attempts have started through a BSc diploma. This paper sums up these different collaborations and directions.

International audience; In this paper, we investigate the application of optical code division multiple access (OCDMA) to multimedia transmission (voice, data, video). The various services are differentiated by assigning to each user a specific two-dimensional (2D) code signature. The coding method used is adapted from 2D multi-wavelength optical orthogonal codes (MWOOC). We first generate 2D multi-weight codes to differentiate the quality of service (QoS). Then, by applying a parallel mapping technique, we achieve multi-rate services. The theoretical error probability corresponding to the quality of each service is established in the noiseless case. This permits evaluating the potentiality of such systems in terms of number of communicating users and data rates. This study has been realized considering a conventional correlation receiver (CCR) with and without hard limiting (HL) device.

International audience; La formation post-capes en information-documentation dans l’Enseignement agricole est basée sur l’alternance et la co-évaluation. Dans ce contexte, la formation peut-elle permettre la construction d'un socle commun de connaissances nécessaires à l'exercice de tous les aspects du métier en prenant en compte les parcours diversifiés ? Un dispositif innovant a été mis en place, au travers duquel les formateurs ont souhaité inscrire un espace de médiation pour permettre une appropriation des contenus sous la forme d’un projet personnel. Ce suivi multiforme est questionné ici afin de mesurer en quoi l'évolution du support de formation et les modalités de diffusion des contenus participent au processus de construction des connaissances dans l'environnement d’enseignement spécifique de futurs professionnels de l'information documentation.

This paper introduces new studies on the codes named Super Orthogonal Space Time Trellis Codes (SOSTTC). Using set partitioning rules combined with a set of orthogonal designs, SOSTTC's are able to combine the coding gain of STTC's together with diversity advantage of orthogonal STBC's. We propose new application fields of these codes in the particular context of three transmit antenna systems. We introduce new STTC's built on STBC designs that outperform some STTC's schemes based on the determinant and rank criteria. Further- more, we demonstrate by simulation that the use of these codes in a turbo parallel concatenated scheme permits working very close to the channel outage probability.

International audience; Metamorphic high electron mobility transistor (MHEMT) technology is well adapted to optical high bit rate telecommunication systems. In this context, we propose in this paper a global analysis of this technology in order to verify if it is suitable for system conditions in terms of on-state and off-state breakdown voltages, ft and fmax, ... Our interest concerns the transistor parasitic effects and their impact on the amplifier circuit performances, considering the transistor role in transmitter and receiver modules. We propose new electrical models for each experimentally measured parasitic effect and they could be added to the MHEMT basic models for circuit design.

This paper addresses Maximum-Likelihood (ML) time synchronization algorithm joint with channel estimation for MIMO-OFDM systems in frequency selective fading channels. For this purpose a SISO joint Maximum likelihood (ML) synchronization algorithm with channel estimation is extended and generalised to MIMO systems. Timing failure probability is presented as a criterion to illustrate the robustness of the algorithm. The performance of the proposed synchronization approach, in terms of timing failure probability, was compared with SISO systems. Based on simulation results, the performance of the proposed algorithm is quite satisfying.

Metamorphic HEMT, MHEMT (InP based layers on GaAs substrate), which are devices still in development, show very promising performances for high bit rate optical links, but still present limitations. In this paper, we propose different new electrical models of detrimental effects affecting the Metamorphic HEMT (MHEMT) functioning. First, we measured devices, particularly in terms of DC characteristics, gate and drain lag effects and on-state and off-state breakdown voltages. Then, we put into evidence the impact ionization mechanism developed in the active layer, and particularly its consequence on the drain current, the gate current and the on-state breakdown voltage. We propose electrical models for the impact ionization, the kink effect, the gate current bell shape model representative of the impact ionization mechanism. Another one permits to take into account the increase of drain current due to the MHEMT burnout (specification of the safe operating area of the MHEMT). All these models have been developed in order to be inserted into a cascade amplifier simulated with ADS software.

In this paper, we study the Parallel Interference Cancellation receiver (PIC) efficiency, in Direct Sequence Optical Code Division Multiple Access system (DS-OCDMA) with Prime Codes (PC). We develop the analytical expression of the error probability in the chip synchronous case, for PC. We show that the PIC receiver permits to suppress totally the effect of Multiple Access Interference (MAI) for Prime Codes, and leads to an error free O-CDMA link in the noiseless case, for whichever PC employed. Simulation results have validated the theoretical analysis. Finally, we show that the PIC receiver permits to reduce the required code length for a given Bit Error Rate.

This paper reports simulation results of transmission performances after introduction of DFB laser diode parameters variations versus time extrapolated from accelerated tests. Simulations are performed using a system simulator to study the consequence of degradations of the laser diode on system performances (eye diagram, quality factor - Q and binary error rate - BER). The studied link consists in 4x2.5 Gbits/s WDM channels with direct modulation and equally spaced by 0,8 nm around the 1550 nm central wavelength. In this paper, only one channel is assumed to be degraded considering an only one activation energy. Simulation results clearly show that variation of basic parameters such as bias current or central wavelength induces a penalization of dynamic performances of the complete WDM link. Consequences on adjacent channels are pointed out underlying the relation between the variations of eye diagram parameters (height, noise, cross-talk, jitter) and the Q-factor decrease. Variations of optical spectrum density at the output of the demultiplexer are also analyzed showing penalties on the final cross-talk. Different degradation kinetics of aged laser diodes from a same batch have been also implemented to build the final distribution of Q-factor and BER after 25 years finally demonstrating the low impact of such variations. The strong interest of this approach is to evaluate the robustness of a dedicated-technology and to become a complementary tool of actual reliability-testing methods and physics of failure in the context of new reliability modeling approach. We have also highlighted the relevance of failure criteria established by actual qualification standards for high-rate optical telecommunication systems.

International audience; In this paper, we discuss the secure of transfering of medical images. We propose two cryptosystems, the first one is a very fast algorithm by block, the TEA (Tiny Encryption Algo- rithm) and the second is a stream cipher based on Vigenere’s ciphering. We show differences existing between them, especially concerning the combination of the image encryption and the compression. Results applied to medical images are given to illustrate the two methods.; Dans cet article, nous discutons du transfert sécurisé d’images médicales. Nous pro- posons deux cryptosystèmes, le premier d’entre eux est un algorithm très rapide de chiffrement par blocs, le TEA (Tiny Encryption Algorithm) et le second est un chiffrement par flots consti- tuant une variante du chiffrement de Vigenère. Nous indiquons les différences qui exitent entre ces deux systèmes, en particulier en ce qui concerne la combinaison du cryptage d’images et de la compression. Des résultats appliqués à des images médicales illustrent les deux méthodes.

National audience; Dans cet article, nous présentons une méthode de tatouage d'image couleur basée sur le contenu de l'image. Cette approche rend notre méthode robuste aux manipulations géométriques tels que les translations ou le fenêtrage ainsi qu'`a la compression JPEG couleur. Pour acquérir cette robustesse, il faut tout d'abord extraire de l'image des composantes géométriquement invariantes. Le tatouage vient alors se synchroniser `a l'image en s'appuyant sur ses invariants. La technique de tatouage s'appuie elle sur les coefficients de la DCT non arrondis.

This paper describes how in order to evaluate and compare the quality, in terms of trapping mechanisms, of conventional and pseudomorphic HEMTs (S-HEMTs and PM-HEMTs, respectively), isothermal drain current transients and G-R noise analysis have been investigated. The influence of HEMT epitaxial structures, growth techniques (MBE or MOCVD) and surface treatments on electrical performances are then discussed. Finally, the experimental data demonstrates the complementarity of these two techniques.

Bacterial diseases of the nervous system comprise a broad range of diseases with their related pathogens. Many bacterial infections can spread to the nervous system, most of them by the hematogenous route. Some, like bacterial meningitis, represent a high disease burden worldwide, which disproportionally affects young children and deserves vigorous interventions for prevention by vaccination. There is a preponderance of tuberculous meningitis, which still has a poor prognosis, in infants and small children and in patients with AIDS. Along with a significant mortality, a high proportion of patients with bacterial and tuberculous meningitis survive with sequelae, most often in poor-resource healthcare settings. Intracellular bacteria, spirochetes, can also cause meningitis and meningoencephalitis. Leprosy, which affects peripheral nerves, is rarely lethal but can result in significant disabilities. Following the Maternal and Neonatal Tetanus Elimination Initiative, global deaths from neonatal tetanus were dramatically reduced but tetanus still kills infants and adults.

International audience