Bibliographies thématiques / Relais cellule

Littérature scientifique sur le sujet « Relais cellule »

Auteur : Grafiati
Publié le 25 juillet 2024

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Articles de revues sur le sujet "Relais cellule"

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Giraudon, Pascale, Christophe Malcus, Aurélie Chalon, Peggy Vincent, Seng Khuth, Arlette Bernard et Marie-Françoise Belin. « Les astrocytes, cellules relais des interactions neuro-immunes dans le système nerveux central ». Journal de la Société de Biologie 197, no 2 (2003) : 103–12. http://dx.doi.org/10.1051/jbio/2003197020103.

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Viswanathan, H., et S. Mukherjee. « Performance of cellular networks with relays and centralized scheduling ». IEEE Transactions on Wireless Communications 4, no 5 (septembre 2005) : 2318–28. http://dx.doi.org/10.1109/twc.2005.853820.

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Park, Won-Hyoung, et Saewoong Bahk. « Resource management policies for fixed relays in cellular networks ». Computer Communications 32, no 4 (mars 2009) : 703–11. http://dx.doi.org/10.1016/j.comcom.2008.11.039.

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Hindia, Mhd Nour, Moubachir Madani Fadoul, Tharek Abdul Rahman et Iraj Sadegh Amiri. « A Stochastic Geometry Approach to Full-Duplex MIMO Relay Network ». Wireless Communications and Mobile Computing 2018 (2018) : 1–11. http://dx.doi.org/10.1155/2018/8342156.

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Cellular networks are extensively modeled by placing the base stations on a grid, with relays and destinations being placed deterministically. These networks are idealized for not considering the interferences when evaluating the coverage/outage and capacity. Realistic models that can overcome such limitation are desirable. Specifically, in a cellular downlink environment, the full-duplex (FD) relaying and destination are prone to interferences from unintended sources and relays. However, this paper considered two-hop cellular network in which the mobile nodes aid the sources by relaying the signal to the dead zone. Further, we model the locations of the sources, relays, and destination nodes as a point process on the plane and analyze the performance of two different hops in the downlink. Then, we obtain the success probability and the ergodic capacity of the two-hop MIMO relay scheme, accounting for the interference from all other adjacent cells. We deploy stochastic geometry and point process theory to rigorously analyze the two-hop scheme with/without interference cancellation. These attained expressions are amenable to numerical evaluation and are corroborated by simulation results.
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Khan, Aroba, et Abbas Jamalipour. « Moving Relays in Heterogeneous Cellular Networks—A Coverage Performance Analysis ». IEEE Transactions on Vehicular Technology 65, no 8 (août 2016) : 6128–35. http://dx.doi.org/10.1109/tvt.2015.2478775.

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Cho, Sungmin, Youngseok Oh, Heejung Yu et Woongsup Lee. « A New Cellular Network Structure Deploying Shared Relays with Sectorization ». Wireless Personal Communications 94, no 4 (28 septembre 2016) : 2987–99. http://dx.doi.org/10.1007/s11277-016-3761-3.

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Casado, Fanny L. « The Aryl Hydrocarbon Receptor Relays Metabolic Signals to Promote Cellular Regeneration ». Stem Cells International 2016 (2016) : 1–8. http://dx.doi.org/10.1155/2016/4389802.

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While sensing the cell environment, the aryl hydrocarbon receptor (AHR) interacts with different pathways involved in cellular homeostasis. This review summarizes evidence suggesting that cellular regeneration in the context of aging and diseases can be modulated by AHR signaling on stem cells. New insights connect orphaned observations into AHR interactions with critical signaling pathways such as WNT to propose a role of this ligand-activated transcription factor in the modulation of cellular regeneration by altering pathways that nurture cellular expansion such as changes in the metabolic efficiency rather than by directly altering cell cycling, proliferation, or cell death. Targeting the AHR to promote regeneration might prove to be a useful strategy to avoid unbalanced disruptions of homeostasis that may promote disease and also provide biological rationale for potential regenerative medicine approaches.
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Sherman, S. M., et R. W. Guillery. « Functional organization of thalamocortical relays ». Journal of Neurophysiology 76, no 3 (1 septembre 1996) : 1367–95. http://dx.doi.org/10.1152/jn.1996.76.3.1367.

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The thalamus has long been seen as responsible for relaying information on the way to the cerebral cortex, but it has not been until the last decade or so that the functional nature of this relay has attracted significant attention. Whereas earlier views tended to relegate thalamic function to a simple, machine-like relay process, recent research, reviewed in this article, demonstrates complicated circuitry and a rich array of membrane properties underlying the thalamic relay. It is now clear that the thalamic relay does not have merely a trivial function. Suggestions that the thalamic circuits and cell properties only come into play during certain phases of sleep to effectively disconnect the relay are correct as far as they go, but they are incomplete, because they fail to take into account interesting and variable properties of the relay that, we argue, occur during normal waking behavior. Although the specific function of the circuits and cellular properties of the thalamic relay for waking behavior is far from clear, we offer two related hypotheses based on recent experimental evidence. One is that the thalamus is not used just to relay peripheral information from, for example, visual, auditory, or cerebellar inputs, but that some thalamic nuclei are arranged instead to relay information from one cortical area to another. The second is that the thalamus is not a simple, passive relay of information to cortex but instead is involved in many dynamic processes that significantly alter the nature of the information relayed to cortex.
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Radunovic, Boz˘idar, et Alexandre Proutiere. « On Downlink Capacity of Cellular Data Networks With WLAN/WPAN Relays ». IEEE/ACM Transactions on Networking 21, no 1 (février 2013) : 286–96. http://dx.doi.org/10.1109/tnet.2012.2198072.

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Chen, Yangyang, Feng Yan et Xavier Lagrange. « Performance analysis of cellular networks with mobile relays under different modes ». Telecommunication Systems 66, no 2 (2 février 2017) : 217–31. http://dx.doi.org/10.1007/s11235-017-0284-5.

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Thèses sur le sujet "Relais cellule"

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Timus, Bogdan. « Studies on the Viability of Cellular Multihop Networks with Fixed Relays ». Doctoral thesis, KTH, Kommunikationssystem, CoS, 2009. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-10526.

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The use of low cost fixed wireless relays has been proposed as a way to deploy high data-rate networks at an affordable cost. During the last decade, significant academic and industrial research has been dedicated to relays. Protocol architectures for cellular-relaying networks are currently considered for standardization as part of both IEEE 802.16 and 3GPP. Various relaying techniques have successfully been commercialized over the years. This dissertation concentrates on the particular case of large scale use of low cost relays, for which focus is put on signal processing and radio resource allocation, rather than on antenna and radio frequency (RF) design, or on network planning. A key question is how low relay cost is low enough for a relaying architecture to be viable from an economic point of view? We develop a framework for evaluating the viability of relaying solutions. The framework is based on a comparison between the relaying architectures and traditional single-hop cellular architectures. This comparative analysis is done from an operator perspective, and is formulated as a network-dimensioning problem. The associated investment decisions are based on financial measures (cost or profit) and taken under technical constraints (throughput, coverage, etc.).First, we consider a large number of traditional dimensioning scenarios, in which the radio network is design for a predefined traffic demand and target quality of service level. We show that the use of low cost relays can indeed be viable, but that the cost savings vary strongly from case to case and often are only modest. Due to the half-duplex nature of the low cost relays, these relays are best suited for providing coverage to guaranteed data-rates, at low end-to-end spectral efficiency, and in environments with strong shadow fading. The type of environment and the placement of relays are more important than the specific protocols and algorithms used in the network. Therefore, traditional network planning remains an essential and challenging task, which is unlikely to be replaced by large-scale (unplanned) use of relays.Second, we suggest a new direction of research in which the viability of relays is judged considering the entire life cycle of a radio network. We give several examples in which the temporary use of relays is economically viable, especially if the service uptake is slow or the uncertainty about the future demand is high. This is particularly relevant if the last-mile cost of a network is dominated by the backhaul transmission cost, and if relaying is implemented as a feature of an access point, rather than as a new device type.
QC 20100812
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Khan, Aroba. « Network Modeling in Heterogeneous and Cooperative Cellular Communications ». Thesis, The University of Sydney, 2016. http://hdl.handle.net/2123/15436.

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The rapid increase in use of smart phones and devices has introduced a growing demand in data traffic which the conventional homogeneous macro cells can no longer satisfy. A promising solution to this is by spectrum reuse through deploying various low-power small cells overlaid on the macro cell. This represents the heterogeneous cellular network that we see today. The change from homogeneous to heterogeneous environment requires new cellular network models to be developed. This thesis presents various novel approaches and models for both homogeneous and heterogeneous cellular networks. Cellular network models aim to provide insights into the performance of the network and its users. One of the most important metrics of network performance and user experience is the signal-to interference- plus-noise-ratio, or SINR. A network operator wanting to optimize the performance of a heterogeneous network needs to know the spatial distribution of the SINR. So, researchers need to carefully consider the network parameters and their spatial distributions while modeling cellular networks. Besides having low-power base stations deployed in hot spot regions, cooperative communication can also be used to improve user performance by reducing the effect of path loss and fading. Considering these facts, the proposed research considers the inclusion of cooperation while modeling cellular networks. Under the proposed scheme, a user in low coverage can use a nearby low-power base station via cooperation to communicate with the macro base station. The main contributions of this thesis can be summarized as below: • A simplified linear cellular network model is proposed which considers the average user distance to determine user performance under a uniform user distribution scenario. This model simplifies the linear grid based model while improving the conventional Wyner model with fading. The proposal is extended to incorporate Gaussian based non-uniform distribution of users within macro cells. The effect of cooperation on user performance is also included in the proposed model where a cell boundary user can use a nearby low-power base station as relay. Mathematical models for analytically evaluating both downlink and uplink transmissions are developed in a multi-cell scenario. The user distributions of interfering neighboring cells are also taken into account. • A two-dimensional heterogeneous cellular network model is developed which considers a realistic spatial distribution of both macro and low-power base stations. For avoiding the probability of severe interference caused by Poisson point process distributed macro base stations, the proposed model considers a grid based distribution for macro base stations and a random distribution for the low-power base stations. Cooperative communication is included in the proposed model where the low-power base stations can act as relays for macro users that are in low coverage. Mathematical models for analytically evaluating user outage and coverage performance is formulated. • A large number of the total cellular network users today are vehicular, i.e. traveling in public transports while using cellular connectivity. The signal strength inside vehicles are attenuated by vehicle penetration loss and hence, becomes weak. To solve this issue, recently researchers have proposed the use of moving relays (MRs) which are mounted on top of public transportation vehicles. However, the impact of having MRs in current heterogeneous cellular networks is not yet investigated. A network model is proposed which considers the presence of MRs on top of suburban trains and derives coverage performance of both vehicular and non-vehicular users for downlink. The effect of MRs in the overall network performance is also evaluated. • Cellular network modeling for uplink is generally known to be difficult since both signal and interference become user location dependent. Moreover, due to power control the transmission power of users varies across cell locations which complicate the analysis to a greater extent. A heterogeneous network model is proposed for uplink with the presence of MRs on suburban trains. Per-user fractional power control is considered and both vehicular and non-vehicular user outage performance is derived. • Cooperative communication via MRs is also included in the proposed heterogeneous network models for both uplink and downlink. According to the proposal, a train traveling in the macro cell with a MR mounted on top can be used as a relay for nearby non-vehicular users in low coverage. Different traveling directions for the train within macro cells are considered and the effect of cooperation via MR on user performance is analyzed for each case. Extensive simulations are carried out for evaluating network performance, which demonstrate the capability of the proposed models in substantially enhancing the performance. The performance evaluation is established with the inclusion of cooperation and MRs in the proposed heterogeneous cellular network models.
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Savard, Anne. « Codage pour les communications coopératives : Codage de source distribué et canaux à relais ». Thesis, Cergy-Pontoise, 2015. http://www.theses.fr/2015CERG0774/document.

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L'augmentation du trafic sur les réseaux sans fil ne permet plus de traiter les données en utilisant les protocoles standard des réseaux filaires, qui sont eux sans interférences. Ainsi, les nœuds des réseaux sans fil doivent coopérer en exploitant les corrélations inhérentes à la proximité des utilisateurs afin d'exploiter au mieux la capacité d'un tel réseau.Dans cette thèse, nous considérons tout d'abord le problème de codage de source avec information adjacente compressée. Le nœud coopératif, ayant accès à un signal corrélé avec celui de la source, peut en envoyer une version compressée au destinataire sur un lien indépendant, permettant d'économiser du débit sur le lien principal. En utilisant une caractérisation des cellules de Voronoi du quantificateur utilisé, nous avons pu améliorer un algorithme de décodage itératif basé sur des codes LDPC.La seconde partie de la thèse traite des problèmes de codage de canal, où les nœuds coopératifs sont des relais. L'exemple le plus simple d'une telle communication est le canal à relais, où un relais aide à la communication entre la source et la destination. Alors que dans le problème de codage de source, le canal de corrélation entre la source et le nœud coopératif est fixé, dans le codage de canal, la question est de savoir quelle opération effectuer au relais. Tout d'abord, nous considérons un problème quelque peu dual au problème de codage de source avec information adjacente compressée, en considérant des bruits corrélés au relais et la destination. Puis, nous étudions des bornes sur la capacité et des débits atteignables pour deux extensions du canal à relais, le canal à relais bidirectionnel avec des bruits corrélés au relais et aux destinations, où deux sources échangent leurs données avec l'aide d'un relais, et le canal multidirectionnel avec liens directs (qui modélisent la proximité des utilisateurs), où les utilisateurs sont regroupés dans des clusters et échangent leurs données localement au sein d'un même cluster avec l'aide d'un relais
The current wireless data traffic growth cannot be handled by classical multi-hop network protocols as in interference-free wired networks, thus it has been recognized that network nodes need to cooperate in order to take advantage of source and/or channel signal correlations, which is needed to achieve fundamental capacity limits.This thesis first considers a cooperative source coding problem, namely binary source coding with coded side information (CoSI): the helper node has access to a signal that is correlated with the source and may send a compressed version on a separate link to the destination, thus rate can be saved on the main source-destination link. Using a characterization of the Hamming-space Voronoi regions of the quantizer at the helper node, an improved practical scheme based on LDPC codes is proposed.The second part of the thesis considers cooperative channel coding, where helper nodes are relays. The simplest example of such a communication is the relay channel, in which a relay node helps the source to send its message to the destination. Whereas in the source coding problem, the correlation between source and side information is given, in channel coding, the main question is to find the best relaying operation. First, a somewhat dual problem to source coding with CoSI is studied, by considering correlated noises at the relay and destination. Then, various extensions of the relay channel are characterized using upper bounds on capacity and achievable rates: the two-way relay channel with correlated noises at the relay and destinations, where two sources wish to exchange their data with the help of a relay, and the multiway relay channel with direct links, where users, grouped into fully connected clusters (users in a cluster can overhear each others' messages), wish to exchange their messages locally within a cluster with the help of one relay
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Negi, Ansuya. « Analysis of Relay-based Cellular Systems ». PDXScholar, 2006. https://pdxscholar.library.pdx.edu/open_access_etds/2668.

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Relays can be used in cellular systems to increase coverage as well as reduce the total power consumed by mobiles in a cell. This latter benefit is particularly useful for mobiles operating on a depleted battery. The relay can be a mobile, a car or any other device with the appropriate communication capabilities. In thesis we analyze the impact of using relays under different situations. We first consider the problem of reducing total power consumed in the system by employing relays intelligently. We find that in a simulated, fully random, mobile cellular network for CDMA (Code Division Multiple Access), significant energy savings are possible ranging from 1.76 dB to 8.45 dB. In addition to reducing power needs, relays can increase the coverage area of a cell by enabling mobiles located in dead spots to place relayed calls. We note that use of relays can increase the useful service area by about 10% with real life scenarios. We observe that in heavy building density areas there is more need of relays as compared to low building density areas. However, the chance of finding relays is greater in low building density areas. Indeed, having more available idle nodes helps in choosing relays, so we conclude that unlike present day implementations of cellular networks, the base station should admit more mobiles (beyond the capacity of the cell) even if they are not placing calls since they can be used as relays. One constraint of using relays is the potential to add interference in the same cell and in neighboring cells. This is particularly true if the relays are not under power control. Based on our analysis, we conclude that in interference limited systems like CDMA the relays have to be under power control otherwise we will reduce the total capacity by creating more dead spots. Thus, we believe that either the base station should be responsible to allocate relays or relays should be provided with enough intelligence to do power control of the downlink. Finally, we show how utility of data services can be increased by use of relays.
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Fraser, Patrick. « Réorganisation des cellules relais et des interneurones gabaergiques du système visuel thalamofuge suite à une lésion rétinienne précoce chez le pigeon / ». Thèse, Trois-Rivières, Université du Québec à Trois-Rivières, 1999. http://www.uqtr.ca/biblio/notice/resume/03-2205947R.html.

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Fraser, Patrick. « Réorganisation des cellules relais et des interneurones gabaergiques du système visuel thalamofuge suite à une lésion rétinienne précoce chez le pigeon ». Thèse, Université du Québec à Trois-Rivières, 1999. http://depot-e.uqtr.ca/3374/1/000663224.pdf.

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Lu, Wei. « New Results on Stochastic Geometry Modeling of Cellular Networks : Modeling, Analysis and Experimental Validation ». Thesis, Université Paris-Saclay (ComUE), 2015. http://www.theses.fr/2015SACLS253/document.

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L'hétérogénéité et l’irrégularité croissante des déploiements des réseaux sans fil de nouvelles générations soulèvent des défis importants dans l’évaluation de performances de ces réseaux. Les modèles classiques s’appuyant sur des modèles hexagonaux pour décrire les emplacements géographiques des nœuds de transmission sont difficilement adaptables à ces réseaux. Dans ce contexte, il a été proposé un nouveau paradigme de modélisation des réseaux sans fil qui s’appuie sur les processus ponctuels de Poisson (PPP), et de manière générale sur la géométrie stochastique. L'analyse, au travers de ces outils mathématiques, présente une complexité indépendante de la taille du réseau, et permet d’estimer avec précision des quantités pratiques liées aux performances des réseaux cellulaires. Cette thèse a porté sur la faisabilité mathématique de l'approche fondée sur les PPP en proposant de nouvelles méthodes mathématiques d’approximations justes incorporant des modèles de propagation du canal radio. Dans un premier temps, un nouveau cadre mathématique, considéré comme une approche Equivalent-in-Distribution (EiD), a été proposée pour le calcul exact de la probabilité d'erreur dans les réseaux cellulaires. L'approche proposée, s’appuyant donc sur la géométrie aléatoire et des modèles spatiaux, montre une complexité faible en terme d’évaluation numérique et est applicable à un grand nombre de configurations MIMO pour lesquelles nous considérons différentes techniques de modulation et techniques de récupération du signal. Dans un deuxième temps, nous étudions les performances des réseaux cellulaires en présence de relais, où trois processus ponctuels de Poisson modélisent respectivement les nœuds relais, les stations de base, et les terminaux mobiles. Pour ce modèle, nous avons considéré des critères souples d'association. Le cadre mathématique proposé et les résultats associés ont montré que les performances dépendent fortement des exposants des fonctions d’atténuation sur les deux premiers sauts sans fil. Nous montrons aussi qu’une mauvaise configuration du réseau peut amener à des gains négligeables de l’utilisation de cette technique. Enfin, nous considérons la modélisation des réseaux cellulaires au travers d’un PPP et d’un modèle unifié d'atténuation de signal généralisée qui prend en compte deux types de liaisons physiques : line-of-sight (LOS) et non-line-of-sight (NLOS). Un modèle de complexité réduite décrivant les propriétés de la liaison radio a aussi été proposée et permet de prendre en compte dans nos calculs un grand nombre de modèle radio proposés dans la littérature. Les résultats montrent, entre autres, qu’une densité optimale pour le déploiement des BS existe lorsque les liens LOS/NLOS sont classés en fonction de leur charge. Nous comparons nos résultats, s’appuyant donc sur un PPP pour modéliser la position des stations de bases et notre modèle de canal radio, avec des simulations de Monte Carlo décrivant des déploiements réels de stations de bases et un modèle de type blocages de construction empiriques. Une bonne correspondance est observée
The increasing heterogeneity and irregular deployment of the emerging wireless networks give enormous challenges to the conventional hexagonal model for abstracting the geographical locations of wireless transmission nodes. Against this backdrop, a new network paradigm by modeling the wireless nodes as a Poisson Point Process (PPP), leveraging on the mathematical tools of stochastic geometry for tractable mathematical analysis, has been proposed with the capability of fairly accurately estimating the performance of practical cellular networks. This dissertation investigated the mathematical tractability of the PPP-based approach by proposing new mathematical methodologies, fair approximations incorporating practical channel propagation models. First, a new mathematical framework, which is referred to as an Equivalent-in-Distribution (EiD)-based approach, has been proposed for computing exact error probability of cellular networks based on random spatial networks. The proposed approach is easy to compute and is shown to be applicable to a bunch of MIMO setups where the modulation techniques and signal recovery techniques are explicitly considered. Second, the performance of relay-aided cooperative cellular networks, where the relay nodes, the base stations, and the mobile terminals are modeled according to three independent PPPs, has been analyzed by assuming flexible cell association criteria. It is shown from the mathematical framework that the performance highly depends on the path-loss exponents of one-hop and two-hop links, and the relays provide negligible gains on the performance if the system is not adequately designed. Third, the PPP modeling of cellular networks with unified signal attenuation model is generalized by taking into account the effect of line-of-sight (LOS) and non-line-of-sight (NLOS) channel propagation. A tractable yet accurate link state model has been proposed to estimate other models available in the literature. It is shown that an optimal density for the BSs deployment exists when the LOS/NLOS links are classified in saturate load cellular networks. In addition, the Monte Carlo simulation results of the real BSs deployments with empirical building blockages are compared with those with PPP distributed BSs with the proposed link state approximation at the end of this dissertation as supplementary material. In general, a good matching is observed
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HABY, MATTHIAS. « Mecanismes cellulaires impliques dans la modalite de transfert et la modalite oscillatoire des cellules relais du corps genouille lateral dorsal. Etude in vitro ». Paris 6, 1990. http://www.theses.fr/1990PA066158.

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Le corps genouille lateral dorsal (cgld est le relais thalamique de la voie visuelle retinocorticale. Les cellules relais du cgld, comme l'ensemble des cellules relais thalamiques, presentent deux modes de fonctionnement distincts: la modalite de transfert qui correspond a la fonction du cgld en tant que relais visuel et la modalite oscillatoire qui est observe durant l'assouplissement et le sommeil a ondes lentes. Le travail presente dans ce memoire s'interesse a ces deux aspects et analyse les mecanismes cellulaires qui les soutendent. Les experiences ont ete realisees sur des tranches maintenues in vitro au moyen d'enregistrements intracellulaires par la technique de courant impose. Dans la premiere partie de notre travail, nous avons etudie le role des circuits locaux inhibiteurs dans l'integration de l'information retinienne. Nos resultats montrent que le potentiel postsynaptique d'excitation declenche par la stimulation electrique du tractus optique est suivi de deux potentiels postsynaptiques d'inhibition. Le premier est de nature chlore et est du a l'action du gaba sur des recepteurs gabaa tandis que le deuxieme est potassique et est du a l'action du gaba sur des recepteurs gabab. Dans la deuxieme partie nous avons analyse les mecanismes cellulaires a la base du comportement oscillatoire des cellules relais du thalamus. Nos resultats montrent que des modifications ioniques du milieu extracellulaire induisent in vitro des comportements oscillatoires stables: un comportement autooscillant rythmique, un comportement non rythmique necessitant l'activation des recepteurs nmda et un comportement autooscillant en bouffees
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Mantovani, G. « Ruolo delle diverse subunità regolatorie della PKA nella regolazione della proliferazione di cellule endocrine ed endocrino-relate ». Doctoral thesis, Università degli Studi di Milano, 2006. http://hdl.handle.net/2434/30895.

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The two regulatory subunits (R1 and R2) of PKA are differentially expressed in several cancer cell lines and studies indicate distinct roles for these subunits in growth control. In recent years, mutations of genes involved in cAMP signalling and resulting in the constitutive activation of cAMP formation have been identified as cause of endocrine neoplasia. In particular, activating mutations of the ? subunit of the stimulatory G protein gene have been found in about 30-40% of GH secreting pituitary adenomas and in subsets of thyroid, adrenocortical, ovarian and testicular Leydig cell tumors, while mutations of the PKA regulatory subunit 1A gene (PRKAR1A) have been identified in patients with Carney complex, a familial multiple endocrine neoplasia syndrome. This thesis evaluated the expression of the different PKA regulatory subunits (R1A, R2A, R2B) in human pituitary adenomas, cortisol-secreting adrenocortical tumors and melanomas, as well as the effects of selective subunit activation on cell proliferation. Our data indicate that altered PKA R1/R2 ratio characterize most endocrine tumors, when compared with the normal counterpart, and that pharmacological and genetic manipulations able to revert this unbalanced expression are able to induce significant anti-proliferative and pro-apoptotic effectis in human tumoral cells.
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Pandey, Sony. « Does altered expression of growth control genes relate to WT1 in leukemia ? » Kent State University / OhioLINK, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=kent1461592576.

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Livres sur le sujet "Relais cellule"

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Zhang, Jie. Femtocells : Technologies and deployment. Chichester, West Susssex, U.K : Wiley, 2010.

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Zhang, Jie. Femtocells : Technologies and deployment. Chichester, West Susssex, U.K : Wiley, 2010.

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3

Bratko, Aleksandr. Automated control systems and communications : fundamentals of telecommunications. ru : INFRA-M Academic Publishing LLC., 2020. http://dx.doi.org/10.12737/1013017.

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The textbook provides a definition of communication, discusses the types and types of telecommunications, and the requirements for communication. It describes telecommunication signals, their parameters, and methods for converting, encoding, and transmitting various types of messages. The principles of construction of multi-channel transmission systems, their main characteristics, the device of terminal subscriber terminals, operational dispatch communication systems, manual and automatic telephone exchanges are described. The principles of building radio communication facilities and rules for conducting radio exchange are considered. The technical characteristics of radio stations used in the EMERCOM and SBS of Russia are given. The basics of radio-relay, satellite, cellular and trunking communications are described. Meets the requirements of the Federal state educational standard of higher education of the latest generation in the discipline "Automated control systems and communications". It is intended for students of secondary professional educational institutions studying in the specialties 20.02.02 "protection in emergency situations" and 20.02.04 "Fire safety".
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Zhang, Jie. Femtocells : Technologies and deployment. Chichester, West Susssex, U.K : Wiley, 2010.

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Dienel, Samuel J., et David A. Lewis. Cellular Mechanisms of Psychotic Disorders. Sous la direction de Dennis S. Charney, Eric J. Nestler, Pamela Sklar et Joseph D. Buxbaum. Oxford University Press, 2017. http://dx.doi.org/10.1093/med/9780190681425.003.0018.

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Cognitive dysfunction in schizophrenia, including disturbances in working memory, is a core feature of the illness and the best predictor of long-term functional outcome. Working memory relies on neural network oscillations in the prefrontal cortex. Gamma-aminobutyric acid (GABA) neurons in the prefrontal cortex, which are crucial for this oscillatory activity, exhibit a number of alterations in individuals diagnosed with schizophrenia. These GABA neuron disturbances may be secondary to upstream alterations in excitatory pyramidal cells in the prefrontal cortex. Together, these findings suggest both a neural substrate for working memory impairments in schizophrenia and therapeutic targets for improving functional outcomes in this patient population.
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Reissner, Kathryn J., et Peter W. Kalivas. Cellular and Molecular Mechanisms of Addiction. Sous la direction de Dennis S. Charney, Eric J. Nestler, Pamela Sklar et Joseph D. Buxbaum. Oxford University Press, 2017. http://dx.doi.org/10.1093/med/9780190681425.003.0046.

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Exposure to drugs of abuse can be a reinforcing experience that, in vulnerable individuals, can lead to continued use and the development of an addiction disorder. Evidence indicates that the escalation in use and compulsive motivation to obtain the drug is linked to long-lasting cellular changes within the brain reward neurocircuitry. In this chapter we describe the stages of transition in use from social use to habitual relapse, and within that context we describe the implicated neurocircuitry, and the enduring cellular and molecular changes that occur within that circuitry, that may mediate the preoccupation with drug seeking in addiction-vulnerable individuals.
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Singh, Indrasen. Device-to-Device Communication and NOMA. Sous la direction de Niraj Pratap Singh. Glasstree, 2018. http://dx.doi.org/10.20850/9781534204447.

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Device-to-Device (D2D) Communication and Non Orthogonal Multiple Access (NOMA) have become topics of interest for researchers. They are widely recognized as techniques of the next generation cellular wireless networks. D2D technique offers uninterrupted communication among proximate mobile users without transferring data to the base station. This can provide high data rates and power control mechanisms. If D2D direct link distance is more, or the quality of channel is poor then the direct D2D communication gives larger propagation losses. This type of scenarios use relay assisted D2D communication, for improving the transmission capacity and coverage. Where as NOMA ) is one of the many technologies that promise greater capacity gain and spectral efficiency than the present state of the art, and is a candidate technology for 5G cellular networks In this book, fundamentals, state of the art, applications and research challenges of D2D and NOMA have been discussed in simple language
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Hines, Melissa. The Integrative Psychobiology of Early Gender Development. Oxford University Press, 2018. http://dx.doi.org/10.1093/oso/9780190658540.003.0011.

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This chapter describes the role of early testosterone exposure in gender development. It discusses these hormonal influences and how they relate to genetic influences, socialization by others, and self-socialization, in shaping gender development. To illustrate these influences, it focuses primarily on childhood play behavior. This focus is used because childhood play behavior shows large differences between the sex categories boy and girl to which children are assigned at birth. Also, childhood play behavior has been studied extensively, providing perhaps the best example of how a gender-related behavior can be influenced by a range of factors at levels of organization from the cellular to the societal working in concert over time.
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Cuthbert, Bruce N. The Nimh Research Domain Criteria Project. Sous la direction de Dennis S. Charney, Eric J. Nestler, Pamela Sklar et Joseph D. Buxbaum. Oxford University Press, 2017. http://dx.doi.org/10.1093/med/9780190681425.003.0071.

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The Research Domain Criteria (RDoC) project grew from recognized deficiencies in currently used diagnostic schemes for mental illness, such as the Diagnostic and Statistical Manual of Mental Disorders (DSM). While the latter is based on a series of signs and symptoms of illnesses that can co-occur in groups of individuals, without consideration of underlying biological factors, RDoC is based on the increasing ability to relate normal as well as abnormal behavior to particular molecules and circuits in the brain across animal species and humans. Behavioral domains include negative valence systems (e.g., fear and anxiety), positive valence systems (e.g., reward and motivation), cognitive systems, social processes, and arousal and regulatory systems, several of which might be affected in a given DSM disease classification. RDoC is seen as a step toward a “precision psychiatry,” where increasing knowledge of the genetic, molecular, cellular, and circuit basis of mental illness will yield biologically based diagnoses that offer important pathophysiological, treatment, and prognostic implications.
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Stoddard, Frederick J., et Robert L. Sheridan. Wound Healing and Depression. Oxford University Press, 2018. http://dx.doi.org/10.1093/med/9780190603342.003.0009.

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Depression and wound healing are bidirectional processes for adults and children consistent with the conception of depression as systemic. This systemic interaction is similar to the “bidirectional impact of mood disorder on risk for development, progression, treatment, and outcomes of medical illness” generally. And, evidence is growing that the bidirectional impact of mood disorder may be true for injuries and for trauma surgery. Animal models have provided some support that treatment of depression may improve wound healing. An established biological model for a mechanism delaying wound healing is increased cortisol secretion secondary to depression and/or stress, and impaired immune response, in addition or together with the other factors such as genetic or epigenetic risk for depression. Cellular models relate both to wound healing and to depression include cytokines, the inflammatory response (Miller et al, 2008), and cellular aging (Telgenhoff and Shroot, 2005) reflected in shorter leukocyte telomere length (LTL) (Verhoeven et al, 2016). Another model of stress impacting wound healing investigated genetic correlates—immediate early gene expression or IEG from the medial prefrontal cortex, and locomotion, in isolation-reared juvenile rats. Levine et al (2008) compared isolation reared to group reared samples, and found that, immediate gene expression in the medial prefrontal cortex (mPFC) was reduced, and behavioral hyperactivity increased, in juvenile rats with 20% burn injuries. Wound healing in the isolation reared rats was significantly impaired. They concluded that these results provide candidates for behavioral biomarkers of isolation rearing during physical injury, i.e. reduced immediate mPFC gene expression and hyperactivity. They suggested that a biomarker such as IEGs might aid in demarcating patients with resilient and adaptive responses to physical illness from those with maladaptive responses
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Chapitres de livres sur le sujet "Relais cellule"

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Pejanovic-Djurisic, Milica, Enis Kocan et Ramjee Prasad. « Relay Stations in Wireless Cellular Networks ». Dans Ofdm Based Relay Systems for Future Wireless Communications, 59–77. New York : River Publishers, 2022. http://dx.doi.org/10.1201/9781003338970-4.

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Can, Başak. « Cooperative Diversity Schemes and User Scheduling with Fixed Relays for IEEE 802.16j* ». Dans Link Adaptation for Relay-Based Cellular Networks, 65–99. New York : River Publishers, 2022. http://dx.doi.org/10.1201/9781003338765-4.

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Soun, Jennifer, Lu-Aung Yosuke Masudathaya, Arabdha Biswas et Daniel S. Chow. « The Role of Artificial Intelligence in Neuro-oncology Imaging ». Dans Machine Learning for Brain Disorders, 963–76. New York, NY : Springer US, 2023. http://dx.doi.org/10.1007/978-1-0716-3195-9_30.

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AbstractDiagnostic imaging is widely used to assess, characterize, and monitor brain tumors. However, there remain several challenges in each of these categories due to the heterogeneous nature of these tumors. This may include variations in tumor biology that relate to variable degrees of cellular proliferation, invasion, and necrosis that in turn have different imaging manifestations. These variations have created challenges for tumor assessment, including segmentation, surveillance, and molecular characterizations. Although several rule-based approaches have been implemented that relates to tumor size and appearance, these methods inherently distill the rich amount of tumor imaging data into a limited number of variables. Approaches in artificial intelligence, machine learning, and deep learning have been increasingly leveraged to computer vision tasks, including tumor imaging, given their effectiveness for solving image-based challenges. This objective of this chapter is to summarize some of these advances in the field of tumor imaging.
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Can, Başak. « Link Adaptation and Selection Method for OFDM-Based Wireless Relay Networks* ». Dans Link Adaptation for Relay-Based Cellular Networks, 39–63. New York : River Publishers, 2022. http://dx.doi.org/10.1201/9781003338765-3.

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Can, Başak. « Introduction ». Dans Link Adaptation for Relay-Based Cellular Networks, 1–12. New York : River Publishers, 2022. http://dx.doi.org/10.1201/9781003338765-1.

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Can, Başak. « Background on Cooperative Communications and the Systems Considered* ». Dans Link Adaptation for Relay-Based Cellular Networks, 13–37. New York : River Publishers, 2022. http://dx.doi.org/10.1201/9781003338765-2.

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Can, Başak. « Implementation Issues for OFDM(A)-Based Wireless Relay Networks* ». Dans Link Adaptation for Relay-Based Cellular Networks, 119–35. New York : River Publishers, 2022. http://dx.doi.org/10.1201/9781003338765-6.

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Can, Başak. « Hop Adaptive MAC-PDU Size Optimization for Infrastructure-Based Wireless Relay Networks* ». Dans Link Adaptation for Relay-Based Cellular Networks, 101–17. New York : River Publishers, 2022. http://dx.doi.org/10.1201/9781003338765-5.

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Can, Başak. « Conclusions and Future Work ». Dans Link Adaptation for Relay-Based Cellular Networks, 137–40. New York : River Publishers, 2022. http://dx.doi.org/10.1201/9781003338765-7.

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Lou, Yisha, Meng Zhang, Hui Yu, Hanwen Luo et Haiquan Wang. « Resource Allocation for Uplink-Downlink Cellular Network with Small Cells and Relays Enhanced ». Dans Wireless Algorithms, Systems, and Applications, 601–12. Cham : Springer International Publishing, 2014. http://dx.doi.org/10.1007/978-3-319-07782-6_54.

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Actes de conférences sur le sujet "Relais cellule"

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Ali, Ahsan-Abbas, et Zartash Afzal Uzmi. « Relays in Cellular Networks ». Dans the 15th ACM International Symposium. New York, New York, USA : ACM Press, 2019. http://dx.doi.org/10.1145/3345837.3355958.

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Calcev, George, et Jeff Bonta. « Opportunistic Two-Hop Relays for OFDMA Cellular Networks ». Dans 2008 IEEE Globecom Workshops. IEEE, 2008. http://dx.doi.org/10.1109/glocomw.2008.ecp.91.

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Chen, Yangyang, Philippe Martins, Laurent Decreusefond, Feng Yan et Xavier Lagrange. « Stochastic analysis of a cellular network with mobile relays ». Dans GLOBECOM 2014 - 2014 IEEE Global Communications Conference. IEEE, 2014. http://dx.doi.org/10.1109/glocom.2014.7037559.

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Papadogiannis, Agisilaos, Ahmed Saadani et Eric Hardouin. « Exploiting Dynamic Relays with Limited Overhead in Cellular Systems ». Dans 2009 IEEE Globecom Workshops. IEEE, 2009. http://dx.doi.org/10.1109/glocomw.2009.5360731.

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Mukherjee, S., et H. Viswanathan. « Analysis of throughput gains from relays in cellular networks ». Dans GLOBECOM '05. IEEE Global Telecommunications Conference, 2005. IEEE, 2005. http://dx.doi.org/10.1109/glocom.2005.1578418.

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Viswanathan, H., et S. Mukherjee. « Performance of cellular networks with relays and centralized scheduling ». Dans 2003 IEEE 58th Vehicular Technology Conference. VTC 2003-Fall (IEEE Cat. No.03CH37484). IEEE, 2003. http://dx.doi.org/10.1109/vetecf.2003.1285360.

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Dinnis, A. K. « Distribution of relays in a cellular system using multihops ». Dans Fifth IEE International Conference on 3G Mobile Communication Technologies (3G 2004) The Premier Technical Conference for 3G and Beyond. IEE, 2004. http://dx.doi.org/10.1049/cp:20040661.

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Khan, Benish Sharfeen, Sobia Jangsher et Farrukh Bhatti. « Profitable Relay Selection in Cooperative Cellular Network with Mobile Relays ». Dans 2017 IEEE 86th Vehicular Technology Conference (VTC-Fall). IEEE, 2017. http://dx.doi.org/10.1109/vtcfall.2017.8288004.

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Lucas-Estan, M. C., et J. Gozalvez. « Mode selection for Multi-Hop Cellular Networks with Mobile Relays ». Dans 2013 IFIP Wireless Days (WD). IEEE, 2013. http://dx.doi.org/10.1109/wd.2013.6686532.

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Jingping et Wei Yu. « Bandwidth and routing optimization in wireless cellular networks with relays ». Dans 2009 7th International Symposium on Modeling and Optimization in Mobile, Ad Hoc, and Wireless Networks - WiOpt 2009. IEEE, 2009. http://dx.doi.org/10.1109/wiopt.2009.5291613.

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Rapports d'organisations sur le sujet "Relais cellule"

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Negi, Ansuya. Analysis of Relay-based Cellular Systems. Portland State University Library, janvier 2000. http://dx.doi.org/10.15760/etd.2666.

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Delmer, Deborah, Nicholas Carpita et Abraham Marcus. Induced Plant Cell Wall Modifications : Use of Plant Cells with Altered Walls to Study Wall Structure, Growth and Potential for Genetic Modification. United States Department of Agriculture, mai 1995. http://dx.doi.org/10.32747/1995.7613021.bard.

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Our previous work indicated that suspension-cultured plant cells show remarkable flexibility in altering cell wall structure in response either to growth on saline medium or in the presence of the cellulose synthesis inhibitor 2,-6-dichlorobenzonitrile (DCB). We have continued to analyze the structure of these modified cell walls to understand how the changes modify wall strength, porosity, and ability to expand. The major load-bearing network in the walls of DCB-adapted dicot cells that lack a substantial cellulose-xyloglucan network is comprised of Ca2+-bridged pectates; these cells also have an unusual and abundant soluble pectic fraction. By contrast, DCB-adapted barley, a graminaceous monocot achieves extra wall strength by enhanced cross-linking of its non-cellulosic polysaccharide network via phenolic residues. Our results have also shed new light on normal wall stucture: 1) the cellulose-xyloglucan network may be independent of other wall networks in dicot primary walls and accounts for about 70% of the total wall strength; 2) the pectic network in dicot walls is the primary determinant of wall porosity; 3) both wall strength and porosity in graminaceous monocot primary walls is greatly influenced by the degree of phenolic cross-linking between non-cellulosic polysaccharides; and 4) the fact that the monocot cells do not secrete excess glucuronoarabinoxylan and mixed-linked glucan in response to growth on DCB, suggests that these two non-cellulosic polymers do not normally interact with cellulose in a manner similar to xyloglucan. We also attempted to understand the factors which limit cell expansion during growth of cells in saline medium. Analyses of hydrolytic enzyme activities suggest that xyloglucan metabolism is not repressed during growth on NaCl. Unlike non-adapted cells, salt-adapted cells were found to lack pectin methyl esterase, but it is not clear how this difference could relate to alterations in wall expansibility. Salt-adaped cell walls contain reduced hyp and secrete two unique PRPP-related proteins suggesting that high NaCl inhibits the cross-linking of these proteins into the walls, a finding that might relate to their altered expansibility.
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Tschoellitsch, Thomas, Martin Dünser, Matthias Noitz et Michael Türk. Clinical indicators of systemic tissue hypoperfusion (‘shock’) : A protocol for a systematic review and qualitative analysis of the literature. INPLASY - International Platform of Registered Systematic Review and Meta-analysis Protocols, décembre 2022. http://dx.doi.org/10.37766/inplasy2022.12.0047.

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Review question / Objective: The objective of this review is to identify the current scientific evidence on the value of clinical signs to indicate systemic tissue hypoperfusion or shock. Condition being studied: In the literature and clinical studies, shock has traditionally been defined by a drop in arterial blood pressure under a critical threshold, e.g., a systolic blood pressure of 90 mmHg, a mean arterial blood pressure <65 mmHg or a relative drop in systolic blood pressure of ≥40 mmHg. From a pathophysiologic point of view, shock relates to an imbalance between tissue oxygen delivery as well as cellular oxygen consumption and utilization. In most cases, shock results from systemic tissue hypoperfusion with consequent decreased tissue oxygen delivery (commonly referred to as circulatory shock). Impaired cellular oxygen consumption and utilization appear to play contributory roles in specific disease states (e.g., sepsis) or conditions (e.g., intoxications).
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Bingham-Koslowski, N., L. T. Dafoe, M R St-Onge, E. C. Turner, J. W. Haggart, U. Gregersen, C. E. Keen, A. L. Bent et J. C. Harrison. Introduction et sommaire. Natural Resources Canada/CMSS/Information Management, 2022. http://dx.doi.org/10.4095/330002.

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Les articles contenus dans le présent bulletin offrent un résumé complet et une mise à jour de nos connaissances de la géologie côtière et de l'évolution de l'île de Baffin, du bras de mer Labrador-Baffin et des régions côtières environnantes. Cet article d'introduction résume et relie les événements géologiques et tectoniques qui ont contribué à l'évolution du craton et des bassins sédimentaires subséquents s'échelonnant du Protérozoïque au Cénozoïque. Plus précisément, nous examinons la géologie du Précambrien et du Paléozoïque de l'île de Baffin et celle d'occurrences localisées de roches de ces âges dans le sous-sol du bras de mer Labrador-Baffin adjacent; la stratigraphie du Mésozoïque-Cénozoïque ainsi que l'histoire du rift qui rend compte de l'ouverture et de l'évolution du bras de mer Labrador-Baffin; la sismicité de la région; ainsi que le potentiel en ressources minérales (île de Baffin) et en hydrocarbures (à terre et en mer).
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Shomer, Ilan, Ruth E. Stark, Victor Gaba et James D. Batteas. Understanding the hardening syndrome of potato (Solanum tuberosum L.) tuber tissue to eliminate textural defects in fresh and fresh-peeled/cut products. United States Department of Agriculture, novembre 2002. http://dx.doi.org/10.32747/2002.7587238.bard.

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The project sought to understand factors and mechanisms involved in the hardening of potato tubers. This syndrome inhibits heat softening due to intercellular adhesion (ICA) strengthening, compromising the marketing of industrially processed potatoes, particularly fresh peeled-cut or frozen tubers. However, ICA strengthening occurs under conditions which are inconsistent with the current ideas that relate it to Ca-pectate following pectin methyl esterase (PME) activity or to formation of rhamnogalacturonan (RG)-II-borate. First, it was necessary to induce strengthening of the middle lamellar complex (MLX) and the ICA as a stress response in some plant parenchyma. As normally this syndrome does not occur uniformly enough to study it, we devised an efficient model in which ICA-strengthening is induced consistently under simulated stress by short-chain, linear, mono-carboxylic acid molecules (OAM), at 65 oC [appendix 1 (Shomer&Kaaber, 2006)]. This rapid strengthening was insufficient for allowing the involved agents assembly to be identifiable; but it enabled us to develop an efficient in vitro system on potato tuber parenchyma slices at 25 ºC for 7 days, whereas unified stress was reliably simulated by OAMs in all the tissue cells. Such consistent ICA-strengthening in vitro was found to be induced according to the unique physicochemical features of each OAM as related to its lipophilicity (Ko/w), pKa, protonated proportion, and carbon chain length by the following parameters: OAM dissociation constant (Kdiss), adsorption affinity constant (KA), number of adsorbed OAMs required for ICA response (cooperativity factor) and the water-induced ICA (ICAwater). Notably, ICA-strengthening is accompanied by cell sap leakage, reflecting cell membrane rupture. In vitro, stress simulation by OAMs at pH<pKa facilitated the consistent assembly of ICAstrengthening agents, which we were able to characterize for the first time at the molecular level within purified insoluble cell wall of ICA-strengthened tissue. (a) With solid-state NMR, we established the chemical structure and covalent binding to cell walls of suberin-like agents associated exclusively with ICA strengthening [appendix 3 (Yu et al., 2006)]; (b) Using proteomics, 8 isoforms of cell wall-bound patatin (a soluble vacuolar 42-kDa protein) were identified exclusively in ICA-strengthened tissue; (c) With light/electron microscopy, ultrastructural characterization, histochemistry and immunolabeling, we co-localized patatin and pectin in the primary cell wall and prominently in the MLX; (d) determination of cell wall composition (pectin, neutral sugars, Ca-pectate) yielded similar results in both controls and ICA-strengthened tissue, implicating factors other than PME activity, Ca2+ or borate ions; (e) X-ray powder diffraction experiments revealed that the cellulose crystallinity in the cell wall is masked by pectin and neutral sugars (mainly galactan), whereas heat or enzymatic pectin degradation exposed the crystalline cellulose structure. Thus, we found that exclusively in ICA-strengthened tissue, heat-resistant pectin is evident in the presence of patatin and suberinlike agents, where the cellulose crystallinity was more hidden than in fresh control tissue. Conclusions: Stress response ICA-strengthening is simulated consistently by OAMs at pH< pKa, although PME and formation of Ca-pectate and RG-II-borate are inhibited. By contrast, at pH>pKa and particularly at pH 7, ICA-strengthening is mostly inhibited, although PME activity and formation of Ca-pectate or RG-II-borate are known to be facilitated. We found that upon stress, vacuolar patatin is released with cell sap leakage, allowing the patatin to associate with the pectin in both the primary cell wall and the MLX. The stress response also includes formation of covalently bound suberin-like polyesters within the insoluble cell wall. The experiments validated the hypotheses, thus led to a novel picture of the structural and molecular alterations responsible for the textural behavior of potato tuber. These findings represent a breakthrough towards understanding of the hardening syndrome, laying the groundwork for potato-handling strategies that assure textural quality of industrially processed particularly in fresh peeled cut tubers, ready-to-prepare and frozen preserved products.
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Shpigel, Nahum Y., Ynte Schukken et Ilan Rosenshine. Identification of genes involved in virulence of Escherichia coli mastitis by signature tagged mutagenesis. United States Department of Agriculture, janvier 2014. http://dx.doi.org/10.32747/2014.7699853.bard.

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Mastitis, an inflammatory response of the mammary tissue to invading pathogenic bacteria, is the largest health problem in the dairy industry and is responsible for multibillion dollar economic losses. E. coli are a leading cause of acute mastitis in dairy animals worldwide and certainly in Israel and North America. The species E. coli comprises a highly heterogeneous group of pathogens, some of which are commensal residents of the gut, infecting the mammary gland after contamination of the teat skin from the environment. As compared to other gut microflora, mammary pathogenic E. coli (MPEC) may have undergone evolutionary adaptations that improve their fitness for colonization of the unique and varied environmental niches found within the mammary gland. These niches include competing microbes already present or accompanying the new colonizer, soluble and cellular antimicrobials in milk, and the innate immune response elicited by mammary cells and recruited immune cells. However, to date, no specific virulence factors have been identified in E. coli isolates associated with mastitis. The original overall research objective of this application was to develop a genome-wide, transposon-tagged mutant collection of MPEC strain P4 and to use this technology to identify E. coli genes that are specifically involved in mammary virulence and pathogenicity. In the course of the project we decided to take an alternative genome-wide approach and to use whole genomes bioinformatics analysis. Using genome sequencing and analysis of six MPEC strains, our studies have shown that type VI secretion system (T6SS) gene clusters were present in all these strains. Furthermore, using unbiased screening of MPEC strains for reduced colonization, fitness and virulence in the murine mastitis model, we have identified in MPEC P4-NR a new pathogenicity island (PAI-1) encoding the core components of T6SS and its hallmark effectors Hcp, VgrG and Rhs. Next, we have shown that specific deletions of T6SS genes reduced colonization, fitness and virulence in lactating mouse mammary glands. Our long-term goal is to understand the molecular mechanisms of host-pathogen interactions in the mammary gland and to relate these mechanisms to disease processes and pathogenesis. We have been able to achieve our research objectives to identify E. coli genes that are specifically involved in mammary virulence and pathogenicity. The project elucidated a new basic concept in host pathogen interaction of MPEC, which for the best of our knowledge was never described or investigated before. This research will help us to shed new light on principles behind the infection strategy of MPEC. The new targets now enable prevalence and epidemiology studies of T6SS in field strains of MPEC which might unveil new geographic, management and ecological risk factors. These will contribute to development of new approaches to treat and prevent mastitis by MPEC and perhaps other mammary pathogens. The use of antibiotics in farm animals and specifically to treat mastitis is gradually precluded and thus new treatment and prevention strategies are needed. Effective mastitis vaccines are currently not available, structural components and effectors of T6SS might be new targets for the development of novel vaccines and therapeutics.
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