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An epidemiological shift towards the elderly population has occurred in traumatic brain injury (TBI). Age is believed to be one of the strongest prognostic indicators following TBI. Diffuse axonal injury (DAI), a prevalent feature of TBI, is believed to be the primary cause for much of the morbidity and mortality associated with TBI. The pathobiology associated with DAI is believed to occur in response to the primary injury in a progressive, secondary fashion. Though the injury mechanisms behind DAI have been shown to occur at numerous sites along the axon, recent work suggests that the axon initial segment (AIS) may show specific vulnerability to DAI and be the primary site of axonal pathobiogenesis. Despite its established predilection for injury, the mechanisms responsible for the pathobiology remain largely unclear – particularly with regard to the age. The current study aims to shed light on the mechanisms responsible for injury by investigating structural alterations to the AIS following DAI in young and old mice. To address this question we have used a central fluid percussion injury (cFPI) model to induce mild DAI on 22-month old aged mice and 3-month old young mice at 3-hours and 24-hours survival time. Double-labeling fluorescent immunohistochemistry was used to demonstrate colocalization of ankG, an AIS domain marker, and APP, a marker used to establish traumatic axonal injury (TAI). Qualitative-quantitative observations based on confocal microscopy demonstrated an increase in APP accumulation associated with AIS over time, post-injury. Initial segments displaying APP association consistently showed a significant overall shortening in young and aged groups at both survival times. No significant difference in AIS length was detected between AIS populations of young and aged mice. Qualitative findings, however, suggest that AIS degradation could be more profound with age, which could have implications on neuronal outcome.

Traumatic axonal injury (TAI) is a consistent feature of (TBI) and is responsible for much of its associated morbidity. TAI is now recognized to result from progressive/secondary axonal injury, though much remains unknown in regards to the pathobiology and the long-term consequences of axonal injury. TAI has been described in the perisomatic domain, located within the neocortex following mild TBI, and within this domain has been linked to neuronal recovery, not neuronal cell death in the acute setting. Due to technical limitations, our understanding of the long-term fate of this neuronal population and the mechanisms responsible for permitting neuronal survival, recovery and axon regeneration following injury are unknown. The studies presented in this thesis are centered upon the hypothesis that injury within the perisomatic domain is unique, and may allow for enhanced neuronal recovery and axonal regeneration. To address many of these questions, we have utilized a novel model of diffuse brain injury in mice, allowing for the use of transgenic mice to overcome previous limitations in the study of TAI. To address this hypothesis, we first assessed the impact of genetic deletion of cyclophilin D (CypD), a regulator of the mitochondrial permeability transition pore (mPTP), upon TAI within the perisomatic domain. Via this approach it was determined that CypD deletion reduced the number of injured axons by ~50%, indicating that CypD and mPTP formation contribute to TAI in the perisomatic domain. Next, using a fluorescent-based approach, we assessed the temporospatial events associated with TAI, acutely. Here it was determined that the axon initial segment (AIS) is uniquely susceptible to TAI following mild TBI (mTBI) and injury within this domain progresses rapidly to axon disconnection. Last we assessed the long-term fate of axotomized neurons and their associated axonal processes. We report that over a chronic time frame, TAI induces no overt cell death, instead results in significant neuronal atrophy with the simultaneous activation of a somatic program of axon regeneration and recovery of the remaining axonal processes. Taken together, the findings of this work reveal that TAI results in a unique axonal injury that results in a persistent axon regenerative attempt.

Traumatic axonal injury (TAI) contributes to the mortality and morbidity following diffuse traumatic brain injury (TBI). Previous work has shown that following TBI, alterations in the molecular domains of axons result in TAI. It is currently posited that injury induced ionic flux is responsible for activating deleterious proteolytic cascades, resulting in altered distributions of axonal components. However, the underlying mechanism of this progressive pathology remains elusive. This study further explores the hypothesis that altered molecular domains contributes to the progressive intra-axonal changes that characterize TAI. Using a rodent model of impact acceleration TBI we examined the expression of nodal and paranodal domains of myelinated axons in brainstem over a 24 h period post-injury. Western blot analysis was utilized to quantify changes in protein levels of Nav1.6, a prominent component at the node of Ranvier, and Caspr, a constituent of the paranodal tripartite complex. Here we report that diffuse TBI causes an up-regulation of Nav1.6 and a down-regulation of Caspr over a 24 h time-course post-injury. The results of this study support that alterations in the molecular components of the domains of injured axons contribute to the cellular mechanism of TAI and thus provides novel data in the field of TBI research.

Recently, Heusler alloys are studied for their interesting magnetic and electronic properties. These properties are strongly dependent on the crystallographic struc- ture. This work deals with Heusler alloys of the A2BC type. We have powder samples and single-crystaline samples for our study as well. An object of interest was a description of crystallographic structure of the samples, site occupation numbers of each type of atoms and their possible occupation disorder. Pow- der difraction and EXAFS have been measured on the powder samples. Clasical single-crystal diffractions has been meassured on the single-crystaline samples. In the case of a modulated structure in the samples, satelite difractions have been measured too. 1

Les différents processus de dégradation des structures de génie civil induisent une micro, puis macro- fissuration du béton. Celle-ci génère alors une réduction des propriétés mécaniques de l'ouvrage et, à terme, sa perte d'étanchéité. Il est donc nécessaire de fournir des informations quant à la présence et à la taille de fissures pour procéder aux réparations nécessaires et conserver l'intégrité de l'ouvrage. Dans un premier temps, le contrôle du béton ainsi que la morphologie de la fissure réelle sont présentés. La notion de contacts entre ses lèvres est introduite pour définir la problématique de sa caractérisation. La bibliographie montre que les méthodes acoustiques standards ne sont pas adaptées à la caractérisation d'une fissure dans le béton. Deux pistes sont alors identifiées : les ultrasons diffus et l'acoustique non linéaire. Nous présentons dans un second temps la caractérisation de la fissure par analyse du transport de l'énergie suivant une équation de diffusion. Les paramètres associés (diffusivité et dissipation) sont déterminés expérimentalement sur des éprouvettes fissurées sur différentes profondeurs. Nous introduisons et définissons le temps d'arrivée du maximum de l'énergie (ATME) qui s'avère être le paramètre le plus sensible à la partie ouverte d'une fissure. Son évolution au regard des incertitudes de mesure ne permet toutefois pas de caractériser totalement la partie fermée. Une simulation numérique en différences finies est réalisée. Elle met en évidence le rôle des contacts au sein de la partie fermée de la fissure et confirme les observations expérimentales. / The various processes of deterioration of the building structures lead to a micro and macro-cracking of the concrete. Consequently, the mechanical properties of the structure are reduced and, eventually, the building is no longer airtight. It is therefore necessary to supply information regarding the presence and size of cracks to carry out the necessary repairs and keep the integrity of the structure. First, the control of concrete as well as the morphology of the actual crack are presented. The notion of contacts between its lips is introduced to define the problem of its characterization. The bibliography shows that the standard acoustic methods are not adapted for characterizing of a crack in concrete. Two tracks are then identified: the diffuse ultrasound and the nonlinear acoustics. Subsequently, we present the characterization of the crack by analyzing the transport of the energy with a diffusion equation. The associated parameters (diffusivity and dissipation) are experimentally determined on test tubes cracked at different depths. We introduce and define the arrival time of the maximum energy (ATME), which turns out to be the most sensitive parameter to the open part of a crack. Its evolution with regard to the measurement uncertainties does not allow a full characterization of the closed part. A digital modeling in finite differences is performed. It highlights the role of the contacts within the closed part of the crack and confirms the experimental observations. Then, we present the nonlinear acoustics and the associated methods applied to concrete.

National concern over traumatic brain injury (TBI) is growing rapidly. Recent focus is on mild TBI (mTBI), which is the most prevalent injury level in both civilian and military demographics. A preeminent sequelae of mTBI is cognitive network disruption. Advanced neuroimaging of mTBI victims supports this premise, revealing alterations in activation and structure-function of excitatory and inhibitory neuronal systems, which are essential for network processing. However, clinical neuroimaging cannot resolve the cellular and molecular substrates underlying such changes. Therefore, to understand the full scope of mTBI-induced alterations it is necessary to study cortical networks on the microscopic level, where neurons form local networks that are the fundamental computational modules supporting cognition. Recently, in a well-controlled animal model of mTBI, we demonstrated in the excitatory pyramidal neuron system, isolated diffuse axonal injury (DAI), in concert with electrophysiological abnormalities in nearby intact (non-DAI) neurons. These findings were consistent with altered axon initial segment (AIS) intrinsic activity functionally associated with structural plasticity, and/or disturbances in extrinsic systems related to parvalbumin (PV)-expressing interneurons that form GABAergic synapses along the pyramidal neuron perisomatic/AIS domains. The AIS and perisomatic GABAergic synapses are domains critical for regulating neuronal activity and E-I balance. In this dissertation, we focus on the neocortical excitatory pyramidal neuron/inhibitory PV+ interneuron local network following mTBI. Our central hypothesis is that mTBI disrupts neuronal network structure and function causing imbalance of excitatory and inhibitory systems. To address this hypothesis we exploited transgenic and cre/lox mouse models of mTBI, employing approaches that couple state-of-the-art bioimaging with electrophysiology to determine the structural- functional alterations of excitatory and inhibitory systems in the neocortex.

No description available.

En informatique ubiquitaire, l'observation du monde physique et de son "contexte" (une représentation haut niveau de la situation physique) est essentielle. Il existe de nombreux moyens pour observer le contexte. Typiquement, cela consiste en un traitement en plusieurs étapes commençant par la récupération de données brutes issues de capteurs. Diverses technologies de capteurs sont utilisées pour la récupération d'informations de bas niveau sur les activités physiques en cours. Ces données sont ensuite rassemblées, analysées et traitées ailleurs dans les systèmes d'information afin d'offrir une reconnaissance de contexte. Les applications déployées réagissent alors en fonction du contexte/de la situation détecté(e). Parmis les capteurs utilisés, les tags RFID, une technologie émergente, permettent de créer un lien virtuel direct entre les objets physiques et les systèmes d'information. En plus de stocker des identifiants, ils offrent un espace mémoire générique aux objets auxquels ils sont attachés, offrant de nouvelles possibilités d'architectures en informatique omniprésente. Dans cette thèse, nous proposons une approche originale tirant parti de l'espace mémoire offerts aux objets réels par les tags RFID. Dans notre approche, les objets supportent directement le système d'information. Ce type d'intégration permet de réduire les communications requises par le traitement à distance. Pour ce faire, des données sémantiques sont tout d'abord attachées aux objets afin de les rendre auto-descriptifs. Ainsi, les données pertinentes concernant une entité physique sont directement disponibles pour un traitement local. Les objets peuvent ensuite être liés virtuellement grâce à des structures de données dédiées ou ad hoc et distribuées sur les objets eux-mêmes. Ce faisant, le traitement des données peut se faire de façon directe. Par exemple, certaines propriétés peuvent être vérifiées localement sur un ensemble d'objets. Une relation physique peut être déduite directement de la structure de données, d'où le nom de "structures de données tangibles". Vis-à-vis des approches conventionnelles tirant parti des identifiants, notre approche offrent des avantages en termes de vie privée, de mise à l'échelle, d'autonomie et d'indépendance vis-à-vis des infrastructures. Le défi se situe au niveau de son expressivité limitée à cause du faible espace mémoire disponible sur les tags RFID. Les principes sont validés dans deux prototypes aux applications différentes. Le premier prototype est développé dans le domaine de la gestion de déchets afin d'aider le tri et d'améliorer le recyclage. Le deuxième offre des services supplémentaires, tels qu'une assistance lors du montage et de la vérification d'objets composés de plusieurs parties, grâce aux structures de données distribuées sur les différentes parties. / Pervasive computing or ambient computing aims to integrate information systems into the environment, in a manner as transparent as possible to the users. It allows the information systems to be tightly coupled with the physical activities within the environment. Everyday used objects, along with their environment, are made smarter with the use of embedded computing, sensors etc. and also have the ability to communicate among themselves. In pervasive computing, it is necessary to sense the real physical world and to perceive its “context” ; a high level representation of the physical situation. There are various ways to derive the context. Typically, the approach is a multi-step process which begins with sensing. Various sensing technologies are used to capture low level information of the physical activities, which are then aggregated, analyzed and computed elsewhere in the information systems, to become aware of the context. Deployed applications then react, depending on the context situation. Among sensors, RFID is an important emerging technology which allows a direct digital link between information systems and physical objects. Besides storing identification data, RFID also provides a general purpose storage space on objects, enabling new architectures for pervasive computing. In this thesis, we defend an original approach adopting the later use of RFID i.e. a digital memory integrated to real objects. The approach uses the principle where the objects self-support information systems. This way of integration reduces the need of communication for remote processing. The principle is realized in two ways. First, objects are piggybacked with semantic information, related to itself ; as self-describing objects. Hence, relevant information associated with the physical entities are readily available locally for processing. Second, group of related objects are digitally linked using dedicated or ad-hoc data structure, distributed over the objects. Hence, it would allow direct data processing - like validating some property involving the objects in proximity. This property of physical relation among objects can be interpreted digitally from the data structure ; this justifies the appellation “Tangible Data Structures”. Unlike the conventional method of using identifiers, our approach has arguments on its benefits in terms of privacy, scalability, autonomy and reduced dependency with respect to infrastructure. But its challenge lies in the expressivity due to limited memory space available in the tags. The principles are validated by prototyping in two different application domains. The first application is developed for waste management domain that helps in efficient sorting and better recycling. And the second, provides added services like assistance while assembling and verification for composite objects, using the distributed data structure across the individual pieces.

Water is a prerequisite for life on our planet. Due to climate change and pollution, water availability for agricultural production, industry and households is increasingly put at risk. With agriculture being the largest water user as well as polluter worldwide, we estimate anthropogenic nitrogen and phosphorus emissions to fresh water related to global crop production at a spatial resolution level of 5 by 5 arc min and calculate the grey water footprints (GWF) related to EU-27's crop production. A multiregional input-output model is used to trace the the GWF embodied in the final consumption of crop products by the EU-27. The total GWF related to crop production in the EU-27 in 2007 was 1 × 1012 m3/year. Spain contributed about 40% to this total. Production of cereals (wheat, rice and other cereals) take the largest share, accounting for 30% of the GWF, followed by fruits (17%), vegetables (14%), and oil crops (13%). The total agricultural GWF of the EU-27 related to crop consumption was 1830 billion m3/year, which is 3700 m3/year per capita on average. Overall, the EU-27 was able to externalize about 41% of the GWF to the rest of the world through imports of crop products.