Le génome des bactéries vivantes n'est pas une entité statique mais au contraire c'est quelque chose très dynamique évoluant avec le temps. Les bactéries évoluent en acquérant par transfert horizontal des gènes du matériel génétique. C'est le cas des EPEC qui ont acquis l'îlot LEE via ce mécanisme. La protéine H-NS joue un rôle important dans la reconnaissance de cet ADN étranger, dans la liaison à cet ADN et dans la répression de son expression quand ce n'est pas en profit du " fitness " de la bactérie. Comme résultat H-NS régule la majorité des gènes associés à la virulence chez les entérobactéries Salmonella, Yersinia et les EPEC. Les EPEC possèdent une protéine paralogue à H-NS et codée dans le premier opéron de leur îlot LEE, il s'agit de la protéine Ler. Une fois exprimée Ler induit l'expression des 4 opérons restant de la région parmi lesquels LEE5. Ler partage une grande homologie avec H-NS surtout au niveau de leurs domaines de reconnaissance de l'ADN. Malgré cette homologie H-NS réprime LEE5 tandis que Ler l'active. De plus si H-NS est un régulateur global agissant sur plus de 500 gènes chez E. coli Ler est une protéine spécifique qui ne va agir que sur un petit nombre de promoteurs tous impliqués dans la virulence L'étude qualitative et quantitative de l'interaction de H-NS et de Ler avec la région promotrice de LEE5 montre qu'elles partagent globalement les mêmes sites de fixation sur des régions étendues en amont et en aval du +1 de la transcription. Ces sites de fixation sont bien définis d'une dizaine de paires de bases. L'affinité de ces sites pour H-NS est variable. Trois sites de haute affinité pour H-NS ont été identifiés. La séquence de ces sites est similaire à celle du site consensus élaboré en étudiant le promoteur proU(Bouffartigues et al - 2007). Des différences dans l'interaction de ces deux protéines avec le promoteur LEE5 résident surtout autour du +1 et des boîtes -10 et -35. Il s'agit de la première étude comparant la fixation de H-NS et de Ler sur des régions étendues de ce promoteur dans le but d'expliquer la régulation différentielle de ces deux protéines paralogues. L'étude de l'expression de LEE5 in vivo nous a permis de proposer que le mécanisme essentiel d'action de Ler est dirigé contre la répression induite par H-NS et que le taux maximum d'expression du promoteur LEE5 wtobservé dans la souche mutante pour hnsen présence de Ler (en comparaison avec la souche double mutante où Ler est absente) n'est pas dû à une activation directe par Ler mais plutôt à une répression par StpA, sensible à la mutation des sites de haute affinité de H-NS.

This thesis presents a general simulation framework used for evaluating the performance of bilateral teleoperation systems under consistent and controllable network conditions. A teleoperation system is where an operator uses a master device to control a slave robot through a communication link. The communication link between the master and slave has an important impact on the system performance. Network emulation using ns-2 has been proposed as a way of simulating the communication link. It allows for the network conditions to be controlled and for repeatable results. The proposed setup was used to test the performance of a hydraulic actuator under various conditions of wired and wireless networks. Three control schemes were evaluated using various combinations of time delay and packet loss. The system was also tested simulating wireless communication between the master and slave to determine the effects of transmission power and distance on the performance of the system.

Grâce à l’échocardiographie au chevet, il est maintenant reconnu que la dysfonction myocardique a une forte prévalence et coexiste avec le choc distributif tôt dans le sepsis sévère. Dans les deux cas, la réanimation liquidienne représente la première ligne de traitement qui permet de sauver des vies. À ce jour, aucun liquide spécifique n'a pu être déclaré supérieur ou ayant un impact clair sur l’issue du choc septique. L’objectif est donc d'évaluer les impacts moléculaires de la perfusion isovolémique de différents liquides de réanimation sur la dysfonction myocardique induite par l'endotoxine. Des rats adultes se sont fait équiper de voies centrales, injecter en intrapéritonéale avec de l’endotoxine (lipopolysaccharide [LPS], provenant d'E. coli) ou du normal salin (0,9 %; contrôle) et, subséquemment, perfuser (ou non) avec une quantité isovolémique de liquide de remplissage vasculaire (normal salin [NS], albumine [ALB], solution de salin hypertonique [HTS]) pour une période de 6 à 24 heures, suivie d'un monitorage échocardiographique ainsi que d'une évaluation biochimique et histopathologique. Résultats : l’albumine améliore la dysfonction myocardique induite par le LPS en : i) réduisant l’épaisseur relative du ventricule gauche en diastole (LVRWD) (élargissement de l’espace interstitiel et de la teneur en albumine endogène); ii) limitant l'apoptose cardiaque tout en maintenant et en régulant le signal extracellulaire d’activation de la protéine kinase mitogène activée [ERK1-2 MAPK]; iii) favorisant les voies d'expression de l’hème oxygénase-1 [HO-1] et de la NO synthase inductible [iNOS]. La solution saline hypertonique [HTS] a été la seule à permettre une prévention hâtive de la dysfonction myocardique, en plus de réduire l'apoptose cardiaque grâce à une augmentation de l’expression de HO-1. Conclusion : les perfusions isovolémiques de liquides ont des impacts moléculaires distincts sur la dysfonction myocardique induite par l’endotoxine. L’albumine et le salin hypertonique présentent de potentielles propriétés antioxydantes, anti-apoptotiques et anti-oedémateuses. Cependant, d’autres recherches seront nécessaires afin d'approfondir les mécanismes sous-jacentes de ces impacts, afin d'éventuellement modifier certaines pratiques cliniques et d'améliorer la survie des patients atteints de dysfonction myocardique d'origine septique.

This thesis presents a general simulation framework used for evaluating the performance of bilateral teleoperation systems under consistent and controllable network conditions. A teleoperation system is where an operator uses a master device to control a slave robot through a communication link. The communication link between the master and slave has an important impact on the system performance. Network emulation using ns-2 has been proposed as a way of simulating the communication link. It allows for the network conditions to be controlled and for repeatable results. The proposed setup was used to test the performance of a hydraulic actuator under various conditions of wired and wireless networks. Three control schemes were evaluated using various combinations of time delay and packet loss. The system was also tested simulating wireless communication between the master and slave to determine the effects of transmission power and distance on the performance of the system.

No description available.

En la adaptación de las bacterias ante cambios ambientales juegan un importante papel las proteínas asociadas al nucleoide. Estas proteínas presentan una doble función: la estructuración del nucleoide bacteriano y otros procesos relacionados con el ADN como es la regulación de la expresión génica. Una de las proteínas asociadas al nucleoide mejor caracterizada es la proteína H-NS, que se encuentra ampliamente distribuída en bacterias G(-). Una de las características de H-NS es su capacidad de formar dímeros con miembros de la familia de proteínas Hha/YmoA, formando de esta manera complejos represores que intervienen en la regulación de determinados operones, como es el caso del operón hly de E. coli. En este trabajo, y en colaboración con el grupo de RMN de biomoléculas dirigido por el doctor Miquel Pons, se han realizado una serie de trabajos con la intención de conocer mejor las características estructurales de la proteína Hha y su interacción con H-NS, en los que se ha puesto de manifiesto que, aún sin ser unos de los residuos aminoacídicos más afectados en la interacción de Hha con H-NS, la cisteína en posición 18 juega un importante papel en el equilibrio conformacional de Hha cuando interacciona con H-NS. La sustitución de esta cisteína por una isoleucina da lugar a una proteína Hha mutante incapaz de complementar la mutación hha y que provoca una reducción en la tasa de crecimiento de E. coli en condiciones de baja osmolaridad. Este efecto podría venir explicado por la mayor resistencia a la fuerza iónica del medio de la interacción de esta proteína Hha mutante con la proteína H-NS, lo que podría provocar la desregulación de algún gen/es esenciales en condiciones de baja osmolaridad. Una segunda parte de esta Tesis Doctoral está dedicada al gen hns de Y. enterocolitica. Estudios previos realizados en nuestro grupo de investigación pusieron de manifiesto la esencialidad del gen hns en esta bacteria, ya que únicamente es posible obtener mutantes hns en Y. enterocolitica en presencia de algún miembro funcional de la familia de proteínas H-NS. En esta Tesis, nos centramos en el sistema que permite obtener un mutante hns en presencia de la proteína StpA, paráloga a H-NS en E. coli. Los resultados obtenidos permitieron comprobar que la presencia de StpA en Y. enterocolitica provoca drásticas alteraciones en su patrón de expresión proteico, efecto no observado en otras bacterias entéricas, y pusieron de manifiesto la importancia de las proteínas H-NS e YmoA en esta bacteria. La proteína YmoA, que interviene en la termorregulación de la expresión de factores de virulencia en Y. enterocolitica, es homologa a la proteína Hha de E. coli, y también es capaz de interaccionar con H-NS. El análisis de estos resultados ha puesto de manifiesto, por un lado, que la presencia de StpA en Y. enterocolitica simula un incremento no fisiológico en los niveles de proteína H-NS, y por otro lado, la importancia no solo de la presencia de las proteínas H-NS e YmoA en Y. enterocolitica, sino también la importancia de sus niveles relativos, ya que un incremento en los niveles de H-NS o una disminución en los de YmoA provocan una drástica alteración en el patrón de expresión proteico de Y. enterocolitica. / "Hha and YmoA family of proteins: structural studies and regulatory role in Y. enterocolitica"TEXT:H-NS protein is a nucleoid-associated protein, widely dstribute in Gram - bacteria. It has a dual function: nucleoid structure protein and others processes related to DNA like gene expression regulation. This protein is able to both oligomerize and heterodimerize with other proteins. One of the partners of these heterodimers are members of Hha/YmoA family of proteins.In the current work, we carry out the production of both Hha and H-NS proteins in order to perform structural studies by RMN. These studies show that cysteine at position 18 in Hha protein is not one of the most affected aminoacids for Hha/H-NS interaction. However, its location between two α-helix domains suggested that it might be an important residue for Hha conformation during its interaction with H-NS. Our results demonstrated that cys 18 substitution by ile, which hypothetically gives rise to a more open structure, genetates a non-functional protein. In addition, we could observe a toxic effect under low osmolarity condition in E. coli. Finally, a higher stability in H-NS/Hha interaction could be observed.The second part of this work deals with Y. enterocolitica hns gene. hns mutants can only be obtained in this bacteria in presence of some functional members of this protein family. This fact is an evidence of the essenciality of hns in Y. enterocolitica. For instance, an hns mutant can be isolated in presence of stpa gene, which is an hns paralogous gene in E.coli, but not present in Y. enterocolitica. Our results demonstrate that drastic effects in the protein expression pattern of Y. enterocolitica are produced in presence of StpA. The analysis of the previous results gave evidence of the importance of YmoA and H-NS proteins in Y. enterocolitica. Not only the presence of the proteins but also their relative levels turned out to be important, since both an increase in H-NS levels and a decrease in YmoA levels gave rise to a dramatic change in Y. enterocolitica protein expression pattern.

Tato práce zkoumá vhodnost a požadavky návrhu simulací pro simulátor NS-3 pro případ bezdrátových sítí používaných v měřící infrastruktuře společnosti Kamstrup. V práci je popsán simulátor NS-3 a je vytvořena základní implementace dvou protokolů. Wireless M-Bus jako příklad jednosměrného protokolu pro zařízení napájené z baterií. Simulace Wireless M-Bus je porovnána s daty naměřenými v reálném systému. NS-3 poskytuje flexibilní prostředí pro vývoj simulací různých síťových protokolů, včetně těch určených pro sítě inteligentních měřidel.

IP networks have become an increasingly protable option over traditional communication networks. Despite the advantages of VoIP compared to PSTN, it is not possible to replace one technology by the other instantly, due to the complexity involved. This implies a transition period in which the two technologies will coexist. In order to make this feasible, there must be a system for mapping E.164 numbers (used in the PSTN) to URIs (used in the IP network). In this context, the ENUM protocol is gaining prominence as the most promising solution. However, it is not very spread yet. In addition, there are technical issues and especially political and economic interests that need to be worked so that this protocol can be popularized. Regarding technical issues, there is a shortage of tools for the study of this protocol. Thus, this dissertation proposes a simulation platform that enables the study of the ENUM protocol. The project design of the simulator was based on experiments carried out in the laboratory, the proposition of mathematical models and, subsequently, implementation, integration and validation of the simulator. The results indicate that the simulation platform rightly describes the real system considered. The results also proved the success of the proposed modeling strategy. In addition, new modules were developed for the NS-3 simulation environment, oering new opportunities for researchers. / As redes IP têm se tornado uma opção cada vez mais vantajosa em relação às redes de comunicações tradicionais. Mesmo diante das vantagens oferecidas pela tecnologia VoIP em relação à PSTN, não é possível uma substituição instantânea de uma tecnologia pela outra devido à complexidade envolvida. Isto implica em um período de transição em que as duas tecnologias irão conviver. Para que isto seja realizável, é necessário que exista um sistema de mapeamento entre números E.164 (utilizados na PSTN) e URIs (utilizados na rede IP). É neste contexto que o protocolo ENUM vem ganhando destaque como a solução mais promissora. Entretanto, a sua disseminação ainda é baixa. Além disso, existem questões técnicas e, principalmente, interesses políticos e econômicos que precisam ser trabalhados para que este protocolo seja popularizado. Em relação às questões técnicas, existe uma escassez de ferramentas para o estudo deste protocolo. Neste sentido, esta dissertação apresenta uma proposta de plataforma de simulação que possibilite o estudo do protocolo ENUM. Dessa maneira, o projeto de concepção do simulador foi baseado na realização de testes em laboratório, na proposição de modelos matemáticos e, posteriormente, na implementação, integração e validação do simulador. Os resultados indicam que a plataforma de simulação descreve com delidade o sistema real considerado. Os resultados também comprovaram o sucesso da estratégia de modelagem proposta. Além disso, novos módulos foram desenvolvidos para o ambiente de simulação NS-3, oferecendo novas possibilidades para os pesquisadores da área. / Mestre em Ciências

This thesis focuses on the enhancement of the IEEE 802.15.4 beaconless-enabled MAC protocol as a solution to overcome the network bottleneck, less flexible nodes, and more energy waste at the centralised wireless sensor networks (WSN). These problems are triggered by mechanism of choosing a centralised WSN coordinator to start communication and manage the resources. Unlike IEEE 802.11 standard, the IEEE 802.15.4 MAC protocol does not include method to overcome hidden nodes problem. Moreover, understanding the behaviour and performance of a large-scale WSN is a very challenging task. A comparative study is conducted to investigate the performance of the proposed ad hoc WSN both over the low data rate IEEE 802.15.4 and the high data rate IEEE 802.11 standards. Simulation results show that, in small-scale networks, ad hoc WSN over 802.15.4 outperforms the WSN where it improves 4-key performance indicators such as throughput, PDR, packet loss, and energy consumption by up to 22.4%, 17.1%, 34.1%, and 43.2%, respectively. Nevertheless, WSN achieves less end-to-end delay; in this study, it introduces by up to 2.0 ms less delay than that of ad hoc WSN. Furthermore, the ad hoc wireless sensor networks work well both over IEEE 802.15.4 and IEEE 802.11 protocols in small-scale networks with low traffic loads. The performance of IEEE 802.15.4 declines for the higher payload size since this standard is dedicated to low rate wireless personal access networks. A deep performance investigation of the IEEE 802.15.4 beaconless-enabled wireless sensor network (BeWSN) in hidden nodes environment has been conducted and followed by an investigation of network overhead on ad hoc networks over IEEE 802.11 protocol. The result of investigation evinces that the performance of beaconless-enabled ad hoc wireless sensor networks deteriorates as indicated by the degradation of throughput and packet reception by up to 72.66 kbps and 35.2%, respectively. In relation to end-to-end delay, however, there is no significant performance deviation caused by hidden nodes appearance. On the other hand, preventing hidden node effect by implementing RTS/CTS mechanism introduces significant overhead on the network that applies low packet size. Therefore, this handshaking method is not suitable for low rate communications protocol such as IEEE 802.15.4 standard. An evaluation study of a 101-node large-scale beaconless-enabled wireless sensor networks over IEEE 802.15.4 protocol has been carried out after the nodes deployment model was arranged. From the experiment, when the number of connection densely increases, then the probability of packet delivery decreases by up to 40.5% for the low payload size and not less than of 44.5% for the upper payload size. Meanwhile, for all sizes of payload applied to the large-scale ad hoc wireless sensor network, it points out an increasing throughput whilst the network handles more connections among sensor nodes. In term of dropped packet, it confirms that a fewer data drops at smaller number of connecting nodes on the network where the protocol outperforms not less than of 34% for low payload size of 30 Bytes. The similar trend obviously happens on packet loss. In addition, the simulation results show that the smaller payload size performs better than the bigger one in term of network latency, where the payload size of 30 Bytes contributes by up to 41.7% less delay compared with the contribution of the payload size of 90 Bytes.

With the advent of new multimedia applications the demand for in time delivery of data is increased as compared to the reliability. Usually the Transport Layer Protocols, User Datagram Protocol (UDP) and Transmission Control Protocol (TCP) are used to transfer the data over the IP based network like Internet. TCP provides a reliable mechanism to transfer the data but its reliable mechanism results in increase in delay. UDP lacks in providing any acknowledgment mechanism and it does not provide any congestion control mechanism also. However the unreliable behavior of UDP results in less delay in data transfer. Now a days one of the important issues is the Quality of Service (QoS) assurance as the behavior of transport layer protocols can affect the QoS. So in order to avoid these issues some new transport layer protocols have been developed by Internet Engineering Task Force (IETF). Two important transport layer protocols, Datagram Congestion Control Protocol (DCCP) and Stream Control Transmission Protocol (SCTP) are used in this study. DCCP is specially designed to avoid congestion in the network. DCCP is suitable for in time delivery of data and also for its congestion control mechanism. DCCP is an unreliable transport layer protocol, as the real time applications demands for in time delivery rather than reliability. SCTP is another transport layer protocol that provides reliable data transfer. In this research work performance of SCTP, DCCP and UDP has been evaluated using MPEG-4 video over Mobile WiMAX/IEEE 802.16e. The performance of these three transport layer protocols is analyzed in terms of performance metrics like packet loss, jitter, delay and throughput. By analyzing these performance measures it is found that the performance of DCCP and SCTP is much better as compared to UDP but DCCP gives much better performance then SCTP when compared in terms of throughput and packet loss. Comparing SCTP and DCCP with UDP in terms of delay and jitter shows that UDP has less delay and jitter as compared to SCTP and DCCP, but because of less throughput and large number of packet loss, UDP can badly degrade the video quality. So, it is found that the DCCP is the most suitable transport layer protocol for transportation of MPEG-4 traffic over Mobile WiMAX/IEEE 802.16e.