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Статті в журналах з теми "Cell transmission models"
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Ahmed, Afzal, Mir Shabbar Ali, and Toor Ansari. "Modelling Heterogeneous and Undisciplined Traffic Flow using Cell Transmission Model." International Journal of Traffic and Transportation Management 02, no. 01 (November 11, 2020): 01–05. http://dx.doi.org/10.5383/jttm.02.01.001.
Повний текст джерелаАнотація:
This research calibrates Cell Transmission Model (CTM) for heterogeneous and non-lane disciplined traffic, as observed in Pakistan and some other developing countries by constructing a flow-density fundamental traffic flow diagram. Currently, most of the traffic simulation packages used for such heterogonous and non-lane-disciplined traffic are not calibrated for local traffic conditions and most of the traffic flow models are developed for comparatively less heterogeneous and lane-disciplined traffic. The flow-density fundamental traffic flow diagram is developed based on extensive field data collected from Karachi, Pakistan. The calibrated CTM model is validated by using actual data from another road and it was concluded that CTM is capable of modelling heterogeneous and non-lane disciplined traffic and performed very reasonably. The calibrated CTM will be a useful input for the application of traffic simulation and optimization packages such as TRANSYT, SIGMIX, DISCO, and CTMSIM.
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Pourbashash, Hossein, Sergei S. Pilyugin, Patrick De Leenheer, and Connell McCluskey. "Global analysis of within host virus models with cell-to-cell viral transmission." Discrete & Continuous Dynamical Systems - B 19, no. 10 (2014): 3341–57. http://dx.doi.org/10.3934/dcdsb.2014.19.3341.
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Fu, Rebecca Menhua, Charlotte Caroline Decker, and Viet Loan Dao Thi. "Cell Culture Models for Hepatitis E Virus." Viruses 11, no. 7 (July 3, 2019): 608. http://dx.doi.org/10.3390/v11070608.
Повний текст джерелаАнотація:
Despite a growing awareness, hepatitis E virus (HEV) remains understudied and investigations have been historically hampered by the absence of efficient cell culture systems. As a result, the pathogenesis of HEV infection and basic steps of the HEV life cycle are poorly understood. Major efforts have recently been made through the development of HEV infectious clones and cellular systems that significantly advanced HEV research. Here, we summarize these systems, discussing their advantages and disadvantages for HEV studies. We further capitalize on the need for HEV-permissive polarized cell models to better recapitulate the entire HEV life cycle and transmission.
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Kumberger, Peter, Karina Durso-Cain, Susan Uprichard, Harel Dahari, and Frederik Graw. "Accounting for Space—Quantification of Cell-To-Cell Transmission Kinetics Using Virus Dynamics Models." Viruses 10, no. 4 (April 17, 2018): 200. http://dx.doi.org/10.3390/v10040200.
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Allen, Linda J. S., and Elissa J. Schwartz. "Free-virus and cell-to-cell transmission in models of equine infectious anemia virus infection." Mathematical Biosciences 270 (December 2015): 237–48. http://dx.doi.org/10.1016/j.mbs.2015.04.001.
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Alimardani, Fatemeh, and John S. Baras. "Performance Assessment of Different Cell-Transmission Models for Ramp-Metered Highway Networks." IFAC-PapersOnLine 54, no. 2 (2021): 114–20. http://dx.doi.org/10.1016/j.ifacol.2021.06.016.
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Recasens, Ariadna, Ayse Ulusoy, Philipp J. Kahle, Donato A. Di Monte, and Benjamin Dehay. "In vivo models of alpha-synuclein transmission and propagation." Cell and Tissue Research 373, no. 1 (November 29, 2017): 183–93. http://dx.doi.org/10.1007/s00441-017-2730-9.
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Graw, Frederik, Danyelle N. Martin, Alan S. Perelson, Susan L. Uprichard, and Harel Dahari. "Quantification of Hepatitis C Virus Cell-to-Cell Spread Using a Stochastic Modeling Approach." Journal of Virology 89, no. 13 (April 1, 2015): 6551–61. http://dx.doi.org/10.1128/jvi.00016-15.
Повний текст джерелаАнотація:
ABSTRACTIt has been proposed that viral cell-to-cell transmission plays a role in establishing and maintaining chronic infections. Thus, understanding the mechanisms and kinetics of cell-to-cell spread is fundamental to elucidating the dynamics of infection and may provide insight into factors that determine chronicity. Because hepatitis C virus (HCV) spreads from cell to cell and has a chronicity rate of up to 80% in exposed individuals, we examined the dynamics of HCV cell-to-cell spreadin vitroand quantified the effect of inhibiting individual host factors. Using a multidisciplinary approach, we performed HCV spread assays and assessed the appropriateness of different stochastic models for describing HCV focus expansion. To evaluate the effect of blocking specific host cell factors on HCV cell-to-cell transmission, assays were performed in the presence of blocking antibodies and/or small-molecule inhibitors targeting different cellular HCV entry factors. In all experiments, HCV-positive cells were identified by immunohistochemical staining and the number of HCV-positive cells per focus was assessed to determine focus size. We found that HCV focus expansion can best be explained by mathematical models assuming focus size-dependent growth. Consistent with previous reports suggesting that some factors impact HCV cell-to-cell spread to different extents, modeling results estimate a hierarchy of efficacies for blocking HCV cell-to-cell spread when targeting different host factors (e.g., CLDN1 > NPC1L1 > TfR1). This approach can be adapted to describe focus expansion dynamics under a variety of experimental conditions as a means to quantify cell-to-cell transmission and assess the impact of cellular factors, viral factors, and antivirals.IMPORTANCEThe ability of viruses to efficiently spread by direct cell-to-cell transmission is thought to play an important role in the establishment and maintenance of viral persistence. As such, elucidating the dynamics of cell-to-cell spread and quantifying the effect of blocking the factors involved has important implications for the design of potent antiviral strategies and controlling viral escape. Mathematical modeling has been widely used to understand HCV infection dynamics and treatment response; however, these models typically assume only cell-free virus infection mechanisms. Here, we used stochastic models describing focus expansion as a means to understand and quantify the dynamics of HCV cell-to-cell spreadin vitroand determined the degree to which cell-to-cell spread is reduced when individual HCV entry factors are blocked. The results demonstrate the ability of this approach to recapitulate and quantify cell-to-cell transmission, as well as the impact of specific factors and potential antivirals.
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Wang, Shaoli, Achun Zhang, and Fei Xu. "Dynamical analysis for delayed virus infection models with cell-to-cell transmission and density-dependent diffusion." International Journal of Biomathematics 13, no. 07 (August 20, 2020): 2050060. http://dx.doi.org/10.1142/s1793524520500606.
Повний текст джерелаАнотація:
In this paper, certain delayed virus dynamical models with cell-to-cell infection and density-dependent diffusion are investigated. For the viral model with a single strain, we have proved the well-posedness and studied the global stabilities of equilibria by defining the basic reproductive number [Formula: see text] and structuring proper Lyapunov functional. Moreover, we found that the infection-free equilibrium is globally asymptotically stable if [Formula: see text], and the infection equilibrium is globally asymptotically stable if [Formula: see text]. For the multi-strain model, we found that all viral strains coexist if the corresponding basic reproductive number [Formula: see text], while virus will extinct if [Formula: see text]. As a result, we found that delay and the density-dependent diffusion does not influence the global stability of the model with cell-to-cell infection and homogeneous Neumann boundary conditions.
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박민주, 권오훈, and Byung-doo JUNG. "Effect Analysis of Bus-exclusive Lane on Traffic Congestion Using Cell Transmission Models." Journal of Transport Research 22, no. 3 (September 2015): 43–53. http://dx.doi.org/10.34143/jtr.2015.22.3.43.
Повний текст джерелаДисертації з теми "Cell transmission models"
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Tarhini, Hussein Ali. "Network Models In Evacuation Planning." Diss., Virginia Tech, 2014. http://hdl.handle.net/10919/64359.
Повний текст джерелаАнотація:
This dissertation addresses the development and analysis of optimization models for evacuation planning. Specifically we consider the cases of large-scale regional evacuation using household vehicles and hospital evacuation.
Since it is difficult to estimate the exact number of people evacuating, we first consider the case where the population size is uncertain. We review the methods studied
in the literature, mainly the strategy of using a deterministic counterpart, i.e., a single deterministic parameter to represent the uncertain population, and we show that these
methods are not very effective in generating a good traffic management strategy. We provide alternatives, where we describe some networks where an optimal policy exist independent of the demand realization and we propose some simple heuristics for more complex ones.
Next we consider the traffic management tools that can be generated from an evacuation plan. We start by introducing the cell transmission model with flow reduction. This model captures the flow reduction after the onset of congestion. We then discuss the management tools that can be extracted from this model. We also propose some simplification to the model formulation to enhance its tractability. A heuristic for generating a solution is also proposed, and its solution quality is analyzed.
Finally, we discuss the hospital evacuation problem where we develop an integer programming model that integrates the building evacuation with the transportation of patients. The impact of building evacuation capabilities on the transportation plan is investigated through the case of a large regional hospital case study. We also propose a decomposition scheme to improve the tractability
of the integer program.Ph. D.
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Maximilien, Jacqueline. "Studies of the impact of core-shell polystyrene nanoparticles on cell membranes and biomimetic models." Thesis, Compiègne, 2015. http://www.theses.fr/2015COMP2180.
Повний текст джерелаАнотація:
L’objectif de ce projet est d’étudier l’interaction de nanoparticules polymères avec les membranes, soit directement sur des cellules entières ou grâce à des modèles membranaires biomimétiques, dans l’optique de valider leur utilisation dans le cadre d’applications biologiques. Des nanoparticules (NPs) polymères cœur/enveloppe avec un diamètre inférieur à 100 nm ont été synthétisés. Cette taille a été choisie afin de leur permettre de pénétrer à travers les membranes plasmiques. Des nanoparticules ayant la même composition chimique mais avec un diamètre hydrodynamique supérieur, de l’ordre de 250 nm, ont été également préparées afin de mettre en évidence l’effet de la taille des particules sur le processus d’internalisation cellulaire. Dans cette thèse, une méthode innovante de synthèse monotope a été développée pour obtenir des NPs coeur-enveloppe, compatibles en milieu aqueux et présentant à leur surface des résidus iniferter. Le coeur est composé de polystyrène avec une taille d’environ 30 nm. Un large éventail de fonctionnalités peut être greffé sur la surface du coeur par polymérisation radicalaire contrôlée en faisant varier différents types de monomères. L’épaisseur de l’enveloppe peut être ajustée en fonction de la concentration en monomère et du temps de polymérisation. Les nanoparticules synthétisées ont été caractérisées par diffusion dynamique de la lumière, par spectroscopie infrarouge à transformée de Fourier, par analyse micro-élémentaire et par microcopie à transmission électronique. Les interactions des NPs à coeur polystyrène et avec des enveloppes de charge neutre et négative ont été étudiées avec des cellules kératinocytes épidermiques humaines néonatales (NHEK), des fibroblastes primaires humains et les cellules HACaT de kératinocytes humains. Les études de cytotoxicité réalisées en utilisant un marquage à l’iodure de propidium et un test à la lactate déshydrogénase n’ont relevé aucune toxicité sur les lignées testées. Cependant, le suivi de la prolifération cellulaire par impédance électrique de substrats cellulaires a indiqué que les nanoparticules anioniques induisent une forte diminution de la prolifération des kératinocytes. L’internalisation cellulaire des NPs a été confirmée par microscopie confocale qui n’indique pas leur colocalisation avec les endosomes précoces, les lysosomes et l’actine. De plus, les données obtenues par triage cellulaire par cytofluorométrie soutiennent qu’un mécanisme énergétiquement-dépendant est mis en œuvre pour l’internalisation des NP neutres, ce qui semble être moins le cas pour les nanoparticules négatives. Les membranes biomimétiques ont été employées afin d’étudier les spécificités des interactions entre nanoparticules et lipides dans des conditions contrôlées. L’étude sur des modèles de vésicules géantes couplée à de la spectroscopie de fluorescence a révélé que les nanoparticules coeur/enveloppe sont capables d’interagir profondément dans la région hydrophobe de la membrane, mais uniquement quand la bicouche lipide est en phase fluide désordonnée. Le mode de pénétration des NPs au travers de la bicouche des vésicules semblent engendrer la formation de pores. Un effet plus prononcé de rigidification de la bicouche a pu être observé lors de l’interaction de nanoparticules chargées négativement avec les bicouches de phosphatidycholines. Cet effet pourrait être attribué à un changement de l’orientation des têtes phosphocholines du à des interactions électrostatiques. En conclusion, les nanoparticules polymère que nous avons synthétisées apparaissent être des outils polyvalents pour les études d’interaction cellulaire et d’imagerie. Ces nanomatériaux peuvent être éventuellement être employés pour la délivrance de médicaments en incorporant les molécules actives dans une enveloppe polymère thermosensible par exempleThis project’s aim was to study polymeric nanoparticle-membrane interactions using both live cells and biomimetic models with the idea to validate such nanoparticles for use in bio-applications. Core-shell polymeric nanoparticles below 100 nm, as this small size is capable of penetrating plasma membranes, were synthesised. Nanoparticles (NPs) with the same chemical composition but with hydrodynamic diameters of ~250 nm, were also prepared in an effort to highlight any effect of NP size on cell internalisation. In this thesis, an innovative method is presented for the synthesis of water-compatible, iniferter-bound polystyrene core shell NPs (~30 nm) using a one-pot synthetic method. A plethora of functionalities could be added to the nanoparticles via shell grafting from the surface of the polystyrene core in the presence of additional monomers via controlled living radical polymerisation. Shell thickness could be tuned as a function of monomer’s concentration and polymerisation time. The nanoparticles were fully characterised by dynamic light scattering, Fourier transform infra-red spectroscopy, microelemental analysis and transmission electron microscopy. Further, the interactions of polystyrene core NPs possessing neutral and anionic shells were investigated using neonatal human epidermal keratinocytes (NHEK), human primary fibroblasts and HaCaT cells. Cytotoxicity studies performed using propidium iodide and lactate dehydrogenase indicated no evidence of cytotoxicity in either cell line. However, cell proliferation monitored by electric cell substrate impedance sensing (ECIS) protocols indicated that anionic nanoparticles induced a dramatic decrease in cell proliferation in keratinocytes. The cellular internalisation of NPs was confirmed by confocal microscopy and no co-localisation was found with early endosomes, lysosomes or actin. Additionally, fluorescence activated cell sorting (FACS) data support the theory that an energy-dependent mechanism is employed for neutral NP internalisation but less so for negatively charged NPs. Biomimetic membrane models were used to investigate specific nanoparticle-lipid interactions under controlled conditions. Employing giant vesicles coupled with fluorescent spectroscopy techniques revealed that core-shell nanoparticles interact deep in the hydrophobic region of bilayers only when the membrane is in the fluid phase. Their mode of entering artificial cells (i.e giant vesicles) appears to cause the formation of pores. Anionic nanoparticles interact with the choline moiety of phosphatidylcholine and confer a rigidifying effect on phosphocholine containing bilayers. Therefore we conclude that the polymeric nanoparticles that we synthesized are versatile tools for cell interaction and imaging studies. These nanomaterials could eventually be applied to drug delivery studies by incorporation of the drug in for instance a thermoresponsive polymeric shell. Furthermore, it is clear that NPs coated with anionic and neutral polymeric shells present a lower toxicity profile than previously reported cationic nanoparticles. Both nanoparticles increase the order lipid bilayer vesicles composed of POPC (the most common glycerophospholipid) in animal and plants. Anionic nanoparticles in particular exhibit a rigidifying effect on POPC lipid bilayers and their mode of entry into cells may be due to the formation of pores which was determined to not induce cell death
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Kacou, Marc Emmanuel Vivien-Marie Wozan. "Design of Models for the Planning of Indoor Multi-technology Wireless Networks." Thesis, Rennes, INSA, 2019. http://www.theses.fr/2019ISAR0010.
Повний текст джерелаАнотація:
L’évolution constante des technologies sans fil telles que le Wi-Fi, les normes de réseaux mobiles ou d’objets connectés, a donné naissance à de nouvelles applications et usages. Les possibilités offertes par cette multitude d’alternatives sont exploitées par les réseaux sans fil hétérogènes qui, en combinant au sein d’un réseau unique plusieurs technologies, permettent aux utilisateurs d’accéder à des services complémentaires de façon transparente. Cependant, pour bénéficier pleinement de ces avantages, plusieurs défis techniques sont à relever. L’un d’eux est relatif au déploiement de ces réseaux multi- technologies. En pratique, cette tâche s’appuie sur des règles et outils d’ingénierie afin de réaliser une planification optimale. Dans ce contexte, un objectif de la thèse a été d’établir des modèles sur lesquels peuvent se baser les outils d’ingénierie radio afin d’optimiser le déploiement de réseau locaux sans fil multi- technologies.Il s’agit principalement de calibrer des modèles de propagation pour l’estimation de couverture radio en environnement indoor résidentiel entre 800 MHz et 60 GHz; d’établir un modèle de débit pour l’estimation de capacité Wi-Fi en fonction du trafic montant et descendant; et de concevoir un modèle de résolution multi-objectif pour optimiser le positionnement de points d’accès opérant à 5 et 60 GHz. En complément, cette thèse a également proposé des recommandations pratiques visant à placer au mieux les points d’accès en phase de déploiement. Cela s’est fait par le biais d’études de sensibilité de couverture à divers facteurs, tels que l’environnement immédiat de l’émetteur ou encore la présence de personnes faisant obstructionThe constant evolution of wireless technologies such as Wi-Fi, mobile networks standards or IoT, has given rise to new applications and usages. The possibilities offered by this multitude of alternatives are exploited by heterogeneous wireless networks which, by combining within a single network several technologies, provide the users with a seamless access to complementary services. However, to take full advantage of these benefits, there are several technical issues to address. One of them is related to the deployment of these multi-technology networks. In practice, this task relies, most of the time, on radio network design software to achieve optimal planning. In such context, the main objective of this thesis is to establish models which can be used by radio network planning tools in order to the deployment of multi-technology wireless local area networks. This task has involved calibrating propagation models for radio coverage estimation, in residential indoor environments from 800 MHz to 60 GHz; developing a throughput model for Wi-Fi capacity estimation based on uplink and downlink traffic; and establishing a multi- objective resolution model to optimize the positioning of access points operating at 5 and 60 GHz. Moreover, this thesis also proposes practical recommendations for a better positioning of access points during deployment phases. This task has been achieved through coverage sensitivity studies to various factors, such as the transmitter surroundings or the presence of obstructing people
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Lee, Sungjoon. "A Cell Transmission Based Assignment-Simulation Model for Integrated Freeway/Surface Street Systems /." Connect to this title online, 1996. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=osu1103731343.
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Velan, Shane M. "The cell-transmission model, a new look at a dynamic network loading model." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2000. http://www.collectionscanada.ca/obj/s4/f2/dsk2/ftp02/NQ55479.pdf.
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Rohde, Jannis [Verfasser]. "Modellerweiterungen des Cell Transmission Model (CTM) für städtische Hauptstraßennetze / Jannis Rohde." Aachen : Shaker, 2017. http://d-nb.info/1138177830/34.
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Ma, Zhiwen. "A combined differential and integral model for high temperature fuel cells." Diss., Georgia Institute of Technology, 2000. http://hdl.handle.net/1853/15831.
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Rohde, Jannis Verfasser], and Bernhard [Akademischer Betreuer] [Friedrich. "Modellerweiterungen des Cell Transmission Model (CTM) für städtische Hauptstraßennetze / Jannis Rohde ; Betreuer: Bernhard Friedrich." Braunschweig : Technische Universität Braunschweig, 2017. http://d-nb.info/1175817988/34.
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Seybold, Christoph. "Calibration of fundamental diagrams for travel time predictions based on the cell transmission model." Thesis, Linköpings universitet, Kommunikations- och transportsystem, 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-118577.
Повний текст джерелаАнотація:
Road traffic increases constantly and the negative consequences in the form of traffic jams can be realized especially in urban areas. In order to provide real time traffic information to road users and traffic managers, accurate computer models gain relevance. A software called Mobile Millennium Stockholm (MMS) was developed to estimate and predict travel times and has been implemented on a 7km test stretch in the north of Stockholm. The core of the software is the cell transmission model (CTM) which is a macroscopic traffic flow model based on aggregated speed observations. This thesis focuses on different calibration techniques of the so called fundamental diagram as an important input factor to the CTM. The diagrams illustrate the mathematical function which defines the relation between traffic flow, density and speed. The calibration is performed in different scenarios based on the least square (LS) and total least square (TLS) error minimization. Furthermore, sources, representing the traffic demand, and sinks, representing the surrounding of the modeled network, are implemented as dynamic parameters to model the change in traffic behavior throughout the day. Split ratios, as a representation of the drivers route choice in the CTM are estimated and implemented as well. For the framework of this work, the MMS software is run in a pure prediction mode. The CTM is based on the source, sink, split and fundamental diagram parameters only and run forward in time. For each fundamental diagram calibration scenario an independent model run is performed. The evaluation of the scenarios is based on the output of the model. The results are compared to existing Bluetooth travel time measurements for the test stretch, which are used as ground truth observations, and a mean average percentage error (MAPE) is calculated. This leads to a most reasonable technique for the fundamental diagram calibration the total least square error minimization.
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Rohde, Jannis [Verfasser], and Bernhard [Akademischer Betreuer] Friedrich. "Modellerweiterungen des Cell Transmission Model (CTM) für städtische Hauptstraßennetze / Jannis Rohde ; Betreuer: Bernhard Friedrich." Braunschweig : Technische Universität Braunschweig, 2017. http://nbn-resolving.de/urn:nbn:de:gbv:084-17010515066.
Повний текст джерелаКниги з теми "Cell transmission models"
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Cronin, Jane. Mathematical aspects of Hodgkin-Huxley neural theory. Cambridge [Cambridgeshire]: Cambridge University Press, 1987.
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W, Kerslake Thomas, Scheiman David A, and NASA Glenn Research Center, eds. Analysis of direct solar illumination on the backside of space station solar cells. [Cleveland, Ohio]: National Aeronautics and Space Administration, Glenn Research Center, 1999.
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Fred, Rieke, ed. Spikes: Exploring the neural code. Cambridge, Mass: MIT Press, 1997.
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Tianjian, Lu, and SpringerLink (Online service), eds. Introduction to Skin Biothermomechanics and Thermal Pain. Berlin, Heidelberg: Springer-Verlag Berlin Heidelberg, 2011.
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(Editor), Siegfried Hoyer, Dorothea M]ller (Editor), and Konstanze Plaschke (Editor), eds. Cell and Animal Models in Aging and Dementia Research (Journal of Neural Transmission). Springer, 1995.
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Hoyer, S. Cell And Animal Models In Aging And Dementia Research (Journal of Neural Transmission Supplementa). Edited by S. Hoyer. Springer, 1994.
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Sadeh, Norman. M-Commerce: Technologies, Services, and Business Models. Wiley & Sons, Incorporated, John, 2008.
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M Commerce: Technologies, Services, and Business Models. Wiley, 2002.
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Byrne, John H., ed. The Oxford Handbook of Invertebrate Neurobiology. Oxford University Press, 2017. http://dx.doi.org/10.1093/oxfordhb/9780190456757.001.0001.
Повний текст джерелаАнотація:
Invertebrates have proven to be extremely useful models for gaining insights into the neural and molecular mechanisms of sensory processing, motor control, and higher functions, such as feeding behavior, learning and memory, navigation, and social behavior. Their enormous contribution to neuroscience is due, in part, to the relative simplicity of invertebrate nervous systems and, in part, to the large cells found in some invertebrates, like mollusks. Because of the organizms’ cell size, individual neurons can be surgically removed and assayed for expression of membrane channels, levels of second messengers, protein phosphorylation, and RNA and protein synthesis. Moreover, peptides and nucleotides can be injected into individual neurons. Other invertebrate systems such as Drosophila and Caenorhabditis elegans are ideal models for genetic approaches to the exploration of neuronal function and the neuronal bases of behavior. The Oxford Handbook of Invertebrate Neurobiology reviews neurobiological phenomena, including motor pattern generation, mechanisms of synaptic transmission, and learning and memory, as well as circadian rhythms, development, regeneration, and reproduction. Species-specific behaviors are covered in chapters on the control of swimming in annelids, crustacea, and mollusks; locomotion in hexapods; and camouflage in cephalopods. A unique feature of the handbook is the coverage of social behavior and intentionality in invertebrates. These developments are contextualized in a chapter summarizing past contributions of invertebrate research as well as areas for future studies that will continue to advance the field.
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Levine, Michael S., Elizabeth A. Wang, Jane Y. Chen, Carlos Cepeda, and Véronique M. André. Altered Neuronal Circuitry. Oxford University Press, 2014. http://dx.doi.org/10.1093/med/9780199929146.003.0010.
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In mouse models of Huntington’s disease (HD), synaptic alterations in the cerebral cortex and striatum are present before overt behavioral symptoms and cell death. Similarly, in HD patients, it is now widely accepted that early deficits can occur in the absence of neural atrophy or overt motor symptoms. In addition, hyperkinetic movements seen in early stages are followed by hypokinesis in the late stages, indicating that different processes may be affected. In mouse models, such behavioral alterations parallel complex biphasic changes in glutamate-mediated excitatory, γ-aminobutyric acid (GABA)-mediated inhibitory synaptic transmission and dopamine modulation in medium spiny neurons of the striatum as well as in cortical pyramidal neurons. The progressive electrophysiologic changes in synaptic communication that occur with disease stage in the cortical and basal ganglia circuits of HD mouse models strongly indicate that therapeutic interventions and strategies in human HD must be targeted to different mechanisms in each stage and to specific subclasses of neurons.
Частини книг з теми "Cell transmission models"
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Bae, Eun-Jin, He-Jin Lee, and Seung-Jae Lee. "Cell Models to Study Cell-to-Cell Transmission of α-Synuclein." In Methods in Molecular Biology, 291–98. New York, NY: Springer New York, 2016. http://dx.doi.org/10.1007/978-1-4939-2978-8_19.
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Roy, Priti Kumar. "T Cell Proliferation." In Mathematical Models for Therapeutic Approaches to Control HIV Disease Transmission, 43–58. Singapore: Springer Singapore, 2015. http://dx.doi.org/10.1007/978-981-287-852-6_3.
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Bompoint, Caroline, Alberto Castagna, Daphna Hutt, Angela Leather, Merja Stenvall, Teija Schröder, Eugenia Trigoso Arjona, and Ton Van Boxtel. "Transplant Preparation." In The European Blood and Marrow Transplantation Textbook for Nurses, 53–75. Cham: Springer International Publishing, 2023. http://dx.doi.org/10.1007/978-3-031-23394-4_4.
Повний текст джерелаАнотація:
AbstractHSCT is a complex procedure, which involves a long and complicated pathway for the patient and the intervention of many health professionals. Within this multidisciplinary team, the transplant coordinator, usually a nurse, is the ‘essential marrow’, the heart and the vital backbone of this procedure; they are an essential transplant ingredient facilitating a fluidity of the pathway and a good transmission of information. Written information about the procedure is beneficial for patients either prior to clinic visit or during clinic to allow the patients and relatives to reflect on conversations. Transplantation carries a significant risk of morbidity and mortality, and these should be considered regarding the ‘need’ to transplant, based upon risk of disease, versus risk of the transplant. Pre-transplant assessments must also be undertaken, and the results of these along with suitable donor medical clearance and cell availability are essential to ascertain that transplant is a valid option and can proceed safely. Dealing with fertility preservation upon diagnosis of cancer is often challenging; this issue is even more complex for paediatric patients. PDWP recommends that counselling about fertility preservation opportunities should be offered to each patient receiving HSCT.This chapter also focuses on vascular access for optimal treatment of haematology patients because stem cell treatment cannot be performed without it. Constant advances in haematology have raised challenging ethical dilemmas concerning end of life, palliative care, patient information, donor concerns and impartiality and issues related to the risk we run to our patients. Nurses provide a key role in patient education, providing pre- and post-transplant advocacy and counselling, plan hospitalisations and consultations. They also act as educators and role models to nursing students and share knowledge in accordance with local policies and JACIE guidelines.
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Peachey, Neal S. "Impaired Transmission from Photoreceptors to Bipolar Cells: Mouse Models." In The Neural Basis of Early Vision, 40. Tokyo: Springer Japan, 2003. http://dx.doi.org/10.1007/978-4-431-68447-3_8.
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Gorman, Julia, Konstantin Holzhausen, Joyce Reimer, and Jørgen Riseth. "Realizing Synaptic Signal Transmission During Astrocyte-Neuron Interactions within the EMI Framework." In Computational Physiology, 65–78. Cham: Springer Nature Switzerland, 2023. http://dx.doi.org/10.1007/978-3-031-25374-4_5.
Повний текст джерелаАнотація:
AbstractThe tripartite synapse or “neural threesome” refers to the interplay in the synapse between neighbouring neurons, the synaptic cleft, and the surrounding glial cells. Despite extensive research, the effects of glial cells, such as astrocytes, on signal transduction between neurons are not fully understood. The Kirchhoff-Nernst- Planck (KNP) and Extracellular-Membrane-Intracellular (EMI) models constitute a promising framework for modeling these kinds of systems. However, they lack the neurotransmitter-related mechanisms that are necessary to bridge signal transduction across the synaptic cleft. Here, we propose an extension to the KNP-EMI model by a spatio-temporal diffusion-based description of the most prominent neurotransmitter, glutamate, that allows for investigation of the contribution of astrocytes to the functionality of the synapse. We validate our model by showing that the presence of an astrocyte in the domain affects the glutamate flux across the postsynaptic terminal, as observed physiologically. The proposed extension offers a sufficiently simple way of integrating synaptic glutamate dynamics into the KNP-EMI framework. It introduces the relevant interactions between electrical activity and diffusion processes at the tripartite synapse that are necessary to assess how astrocytes might contribute to the functionality of the synapse. This work has implications for future studies involving glial mechanisms and other charged species within the KNP-EMI framework.
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Sher, Emanuele, Cecilia Gotti, Diego Fornasari, Bice Chini, Azucena Esparis Ogando, and Francesco Clementi. "Human Neuroblastoma Cells: An in Vitro Model for the Study of Mammalian Neuronal Nicotinic Receptors." In Cellular and Molecular Basis of Synaptic Transmission, 493–506. Berlin, Heidelberg: Springer Berlin Heidelberg, 1988. http://dx.doi.org/10.1007/978-3-642-73172-3_33.
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Hattaf, Khalid, and Noura Yousfi. "Global Properties of a Diffusive HBV Infection Model with Cell-to-Cell Transmission and Three Distributed Delays." In Disease Prevention and Health Promotion in Developing Countries, 117–31. Cham: Springer International Publishing, 2020. http://dx.doi.org/10.1007/978-3-030-34702-4_10.
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Tokuda, Sho, Ryo Kanamori, and Takayuki Ito. "Development of Traffic Simulator Based on Stochastic Cell Transmission Model for Urban Network." In PRIMA 2014: Principles and Practice of Multi-Agent Systems, 150–65. Cham: Springer International Publishing, 2014. http://dx.doi.org/10.1007/978-3-319-13191-7_13.
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Heidecke, J., and M. V. Barbarossa. "When Ideas Go Viral—Complex Bifurcations in a Two-Stage Transmission Model." In Trends in Biomathematics: Chaos and Control in Epidemics, Ecosystems, and Cells, 221–42. Cham: Springer International Publishing, 2021. http://dx.doi.org/10.1007/978-3-030-73241-7_14.
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Dubey, Ved Prakash, Rajnesh Kumar, and Devendra Kumar. "Fractional Order Model of Transmission Dynamics of HIV/AIDS with Effect of Weak CD4+ T Cells." In Fractional Calculus in Medical and Health Science, 149–65. Boca Raton, FL : CRC Press/Taylor & Francis Group, [2021] |: CRC Press, 2020. http://dx.doi.org/10.1201/9780429340567-6.
Повний текст джерелаТези доповідей конференцій з теми "Cell transmission models"
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Arlinda, Rrecaj, Alimehaj Vlera, and Lokaj Drita. "Estimation of Velocities in an Urban Segment through CTM model." In TRANSPORT FOR TODAY'S SOCIETY. Faculty of Technical Sciences Bitola, 2021. http://dx.doi.org/10.20544/tts2021.1.1.21.p18.
Повний текст джерелаАнотація:
Abstract-Because of its close relationship to density and flow, velocity play a key role in prediction of traffic parameters with the purpose of use in real-time traffic control. In this paper is proposed a procedure of estimation of velocities through a macroscopic model that originates from LWR (Lighthill-Whitham-Richards) model called Cell Transmission Model. Beside the possibility to update the densities of cells through time step, the CTM model enables the estimation of evolution of the velocities thanks to some known models that describe these relationships. A case study in an urban segment is treated in order to estimate velocities. Validation of these velocity values is done by comparing the inter cell flows from CTM (Cell Transmission Models) model and flows as function of updates velocities. Keywords –Cell, density, inter cell flow, outflow, velocity, model hypothesis
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McGuire, Nicholas E., Neal P. Sullivan, Robert J. Kee, Huayang Zhu, James A. Nabity, Jeffrey R. Engel, David T. Wickham, and Michael Kaufman. "Hexaaluminate Catalysts for Fuel Reforming." In ASME 2008 6th International Conference on Fuel Cell Science, Engineering and Technology. ASMEDC, 2008. http://dx.doi.org/10.1115/fuelcell2008-65231.
Повний текст джерелаАнотація:
Hexaaluminate catalysts offer excellent high-temperature stability compared to the equivalent metal-based catalysts. Their stability also lends well to use as a catalyst support. However, use of novel hexaaluminates is limited in fuel processing for fuel-cell applications. In this paper, we report on the performance of hexaaluminates as a catalyst support in the steam reforming of methane. The hexaaluminates are synthesized by a metal-exchange process using alumoxane precursors that enable a wide range of metal substitutions. Performance is evaluated using a unique stagnation-flow reactor that enables detailed probing of the boundary layer above the catalyst-impregnated stagnation surface. Experimental results are compared with models to understand fundamental reaction kinetics and optimize catalyst performance. RhSr-substituted hexaaluminates with a Rh impregnation are shown to yield the best performance. Scanning- and Transmission-Electron Microscopy are used to characterize the different types of hexaaluminates, and to examine the effect of aging on catalyst structure.
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Suo-Anttila, Jill, Patrick Drozda, Louis Gritzo, and Mun Young Choi. "Towards Characterization of Soot Morphology, Composition, and Optical Properties From Large Pool Fires." In ASME 2002 International Mechanical Engineering Congress and Exposition. ASMEDC, 2002. http://dx.doi.org/10.1115/imece2002-33972.
Повний текст джерелаАнотація:
The thermal hazard posed by large hydrocarbon fires is dominated by the radiative emission from high temperature soot. Since the optical and morphological properties of soot are not well known, especially in the infrared, efforts to characterize these properties are underway. Measurements of optical properties and morphology in large fires are important in heat transfer calculations, interpretation of laser-based diagnostics, and to build revised soot property models for fire field models. This research utilizes extractive measurement diagnostics to characterize soot morphology, composition, and optical properties in pool fires. The fires of interest are realistic in size, and considerably larger than recent studies, from transitionally turbulent to fully turbulent JP-8 pool fires. For measurement of the extinction coefficient, soot extracted from the flame zone is transported to a transmission cell where measurements are made using both visible and infrared lasers. Soot morphological properties are obtained by analysis via transmission electron microscopy of soot samples obtained thermophoretically within the flame zone, overfire region, and in the transmission cell. Soot composition, including carbon-to-hydrogen ration and PAH concentration, is obtained by analysis of soot collected on filters. In addition to providing insight into optical properties, soot samples obtained allow researchers to determine that the soot morphology is not affected by the transport to the transmission cell. This paper describes the diagnostics and presents some preliminary data for soot morphology, composition, and optical properties measurements within the flame zone of pool fires.
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Kasula, Bhavani V., Leslie Mercado, Pietro Asinari, and Michael R. von Spakovsky. "3D Microstructure Reconstructions of Solid Oxide and Proton Exchange Membrane Fuel Cell Electrodes With Applications to Numerical Simulations of Reacting Mixture Flows Using LBM." In ASME 2007 International Mechanical Engineering Congress and Exposition. ASMEDC, 2007. http://dx.doi.org/10.1115/imece2007-42937.
Повний текст джерелаАнотація:
Computational modeling of fuel cell electrode-catalyst layers is an important tool in understanding the different electrochemical reactions and transport phenomena occurring within fuel cell electrodes. Proper modeling of this layer is required for an accurate prediction of cell behavior which in turn can be used for the development of more efficient fuel cells. In macroscopic CFD approaches such layers are typically modeled as infinitely thin interfaces populated by sources and sinks or as very thin homogeneous porous layers. However, these layers are neither infinitely thin nor homogeneous and, thus, modeling in this fashion leads to a loss of information about the microstructure and its varying effects on the reacting mixture flows which pass through and into the structure. Thus, the utility of relying only on such macroscopic representations limits the general applicability of these macroscopic models as tools for design and for predicting fuel cell performance over a wide range of conditions. Furthermore, such macroscopic models cannot aid in the design of the electrode-catalyst layer itself. In order to address this latter point, a microscopic/mesoscopic modeling approach can be used, e.g., the Lattice Boltzmann Method (LBM), which models the reacting mixture flow through the porous microstructure of the electrode-catalyst layer. However, to do so requires reconstructing the porous geometry of this layer which can be done by using 2D microscopic images of cross-sections of the layer to generate 3D geometries from, for example, stochastic models which are relatively cost efficient and lead to similar structures with approximately the same characteristics of porosity, catalyst loading, three-phase boundaries, etc. as the original structure. Two such 3D reconstruction methods, i.e. one based on the granulometry law (one-point statistics) and the other on two-point statistics, are applied to a 2D SEM (scanning electron microscope) image of an SOFC electrode-catalyst layer and to the 2D SEM and TEM (transmission electron microscope) images for such a layer in a PEMFC. Results for these reconstructions are presented as are results for reacting mixture flow simulations through the two different reconstructed 3D SOFC structures using a 3D LBM approach. The development and application of a 3D LBM model for two-phase reacting mixture flows in PEMFC electrode-catalyst layer structures is in progress and will be reported in a future paper.
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Alvarez-Icaza, Luis, and Genaro J. Islas. "Hysteretic Cell Transmission Model." In 2013 16th International IEEE Conference on Intelligent Transportation Systems - (ITSC 2013). IEEE, 2013. http://dx.doi.org/10.1109/itsc.2013.6728293.
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Bassett, Kyle, and Ino Fleischmann. "An Open Source Licensed Vertical Axis Wind Turbine for Rural Electrification and Sustainability." In ASME 2012 6th International Conference on Energy Sustainability collocated with the ASME 2012 10th International Conference on Fuel Cell Science, Engineering and Technology. American Society of Mechanical Engineers, 2012. http://dx.doi.org/10.1115/es2012-91388.
Повний текст джерелаАнотація:
This paper documents the iterative design and development of six operational vertical axis wind turbine prototypes tailor built for rural electrification projects in Central America. All prototypes have been based on the unique lift type blade system consisting of sailcloth material which allows for the turbine to operate with variable blade pitch and profile camber. The latest prototype is presented along with a detailed discussion of fundamental design aspects such as the sail blades, frame tower, alternator, and transmission systems. The VosREC headquarters for research, development and testing is located in a remote, rural, and non-electrified village in Nicaragua. This location provides researchers with the unique opportunity to experience and observe first-hand how renewable energy technologies can be applied to improve quality of life for people living without connection to national electricity grids. Aspects and benefits of the “open source hardware” approach are presented along with a discussion on implementation models, “bottom-up”, empowerment and self-organization.
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Al-Gahtani, S. F., and R. M. Nelms. "Analytical Study of the Effects of Grid Resistance on Grid-Connected PV Systems: Modeling and Simulation." In ASME 2016 Power Conference collocated with the ASME 2016 10th International Conference on Energy Sustainability and the ASME 2016 14th International Conference on Fuel Cell Science, Engineering and Technology. American Society of Mechanical Engineers, 2016. http://dx.doi.org/10.1115/power2016-59614.
Повний текст джерелаАнотація:
Renewable energy systems have become common in power systems. Many problems associated with connecting a renewable energy system to utility network have arisen. In the traditional power calculation, the resistance of the line is ignored because of large the X/R ratio. However, the R/X ratio in the distribution network is greater than in transmission. Because of that, the line resistance should be considered in the power calculations. In this paper, the effect of the grid resistance on transfer of power is investigated by calculating the active power between a PV system and the grid where the grid resistance is included. Two models were developed to study the effects of the grid resistance. The sensitivity of real and reactive power to the grid impedance, the current performance and the phase angle for the maximum power were studied under variations of the grid resistance. The results from both models have been compared to emphasize that the transfer of power is really influenced by the resistance of the line impedance.
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Ding, G., Y. Fan, X. Lu, F. Pang, Q. Diao, and H. Zhang. "Research on hydrogen-oxygen fuel cell model." In 18th International Conference on AC and DC Power Transmission (ACDC 2022). Institution of Engineering and Technology, 2022. http://dx.doi.org/10.1049/icp.2022.1427.
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de Carvalho, Thiago Piazera, Hervé P. Morvan, and David Hargreaves. "Pore-Level Numerical Simulation of Open-Cell Metal Foams With Application to Aero Engine Separators." In ASME Turbo Expo 2014: Turbine Technical Conference and Exposition. American Society of Mechanical Engineers, 2014. http://dx.doi.org/10.1115/gt2014-26402.
Повний текст джерелаАнотація:
In aero engines, the oil and air interaction within bearing chambers creates a complex two-phase flow. Since most aero engines use a close-loop oil system and releasing oil out is not acceptable, oil-air separation is essential. The oil originates from the engine transmission, the majority of which is scavenged out from the oil pump. The remainder exits via the air vents, where it goes to an air oil separator called a breather. In metal-foam-style breathers separation occurs by two physical processes. Firstly the largest droplets are centrifuged against the separator walls. Secondly, smaller droplets, which tend to follow the main air path, pass through the metal foam where they ideally should impact and coalesce on the material filaments and drift radially outwards, by the action of centrifugal forces. Although these devices have high separation efficiency, it is important to understand how these systems work to continue to improve separation and droplet capture. One approach to evaluate separation effectiveness is by means of Computational Fluid Dynamics. Numerical studies on breathers are quite scarce and have always employed simplified porous media approaches where a momentum sink is added into the momentum equations in order to account for the viscous and/or inertial losses due to the porous zone [1]. Furthermore, there have been no attempts that the authors know of to model the oil flow inside the porous medium of such devices. Normally, breathers employ a high porosity open-cell metal foam as the porous medium. The aim of this study is to perform a pore-level numerical simulation on a representative elementary volume (REV) of the metal foam with the purpose of determining its transport properties. The pore scale topology is represented firstly by an idealized geometry, namely the Weaire-Phelan cell [2]. The pressure drop and permeability are determined by the solution of the Navier-Stokes equations. Additionally, structural properties such as porosity, specific surface area and pore diameter are calculated. The same procedure is then applied to a 3D digital representation of a metallic foam sample generated by X-ray tomography scans [3]. Both geometries are compared against each other and experimental data for validation. Preliminary simulations with the X-ray scanned model have tended to under predict the pressure drop when compared to in-house experimental data. Additionally, the few existing studies on flow in metal foams have tended to consider laminar flow; this is not the case here and this also raises the question that Reynolds-averaged turbulence models might not be well suited to flows at such small scales, which this paper considers.
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Zhou, Xiaozhou, Bin Wang, Christopher Price, Wen Li, Jun Pan, and Liyun Wang. "Investigating the Sieving and Structural Property of the Osteocyte Pericellular Matrix: Experiments and Modeling." In ASME 2012 Summer Bioengineering Conference. American Society of Mechanical Engineers, 2012. http://dx.doi.org/10.1115/sbc2012-80307.
Повний текст джерелаАнотація:
Growing evidence shows that osteocytes, the most abundant bone cells, serve as the primary sensory cells that detect external mechanical forces [1], enabling the bone to adapt its mass and structure to meet its environmental requirements and to fulfill its weight bearing functions [2]. Although the cellular and molecular mechanisms of such adaptation phenomena are not fully understood, recent experiments and theoretical models suggest that the pericellular matrix (PCM) filling the tiny gap between the cell membrane and the canalicular matrix wall plays a critical role in the osteocytes’ outside-in signaling process [1]. Weinbaum first hypothesized that a proteoglycan-like fiber matrix, similar to the endothelial glycocalyx, must exist within the PCM to account for the surprisingly long relaxation times of the strain-generated potentials measured in bone [3]. Such a filling matrix was predicted to impose hydraulic resistance, impede fluid pressure relaxation and reduce fluid flow in the tiny lacunar-canalicular pore system in bone, thus protecting the cell membranes from being ruptured under shear. Later electronic microscopic studies confirmed the existence and the proteoglycan nature of the PCM [4]. Previous models using idealized PCM ultrastructure suggested that the hydrodynamic interactions between the PCM and fluid could determine the magnitude of drag forces that deform cytoskeleton via tethered transmembrane components or the focal contacts containing integrins [5,6]. In both scenarios, the PCM is the key to force transmission and strain signal amplification, and responsible for downstream mechanotransduction. In addition, once the mechanically excited osteocytes affect the release of molecular signals such as ATP, NO, PGE2, OPG, RANKL, and sclerostin [2], the PCM, as a molecular sieve and temporary storage, may influence the transport and availability of these bioactive molecules [7]. Therefore, the structural and sieving properties of PCM are important in regulating bone’s mechanotransduction and adaptation. However, due to the small dimensions of the PCM (∼100nm thick) and the difficulty in preserving the PCM in situ, its detailed structure and properties have remained elusive [4]. The objective of this study was to elucidate the sieving property of the PCM in mechanically loaded bone with an innovative imaging approach and to further deduce plausible PCM structures using mathematical modeling.
Звіти організацій з теми "Cell transmission models"
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Ehrlich, Marcelo, John S. Parker, and Terence S. Dermody. Development of a Plasmid-Based Reverse Genetics System for the Bluetongue and Epizootic Hemorrhagic Disease Viruses to Allow a Comparative Characterization of the Function of the NS3 Viroporin in Viral Egress. United States Department of Agriculture, September 2013. http://dx.doi.org/10.32747/2013.7699840.bard.
Повний текст джерелаАнотація:
Project Title: "Development of a plasmid-based reverse genetics system for the Bluetongue and Epizootic Hemorrhagic Disease viruses to allow comparative characterization of the function of the NS3 viroporin in viral egress". Project details: No - IS-4192-09; Participants – Ehrlich M. (Tel Aviv University), Parker J.S. (Cornell University), DermodyT.S. (Vanderbilt University); Period - 2009-2013. Orbiviruses are insect-borne infectious agents of ruminants that cause diseases with considerable economical impact in Israel and the United States. The recent outbreaks of BTV in Europe and of Epizootic Hemorrhagic Disease Virus (EHDV) in Israel, underscore the need for: (i) a better comprehension of the infection process of orbiviruses, (ii) the identification of unique vs. common traits among different orbiviruses, (iii) the development of novel diagnosis and treatment techniques and approaches; all aimed at the achievement of more effective control and treatment measures. It is the context of these broad goals that the present project was carried out. To fulfill our long-term goal of identifying specific viral determinants of virulence, growth, and transmission of the orbiviruses, we proposed to: (i) develop reverse genetics systems for BTV and EHDV2-Ibaraki; and (ii) identify the molecular determinants of the NS3 nonstructural protein related to viroporin/viral egress activities. The first objective was pursued with a two-pronged approach: (i) development of a plasmid-based reverse genetics system for BTV-17, and (ii) development of an "in-vitro" transcription-based reverse genetics system for EHDV2-Ibaraki. Both approaches encountered technical problems that hampered their achievement. However, dissection of the possible causes of the failure to achieve viral spread of EHDV2-Ibaraki, following the transfection of in-vitro transcribed genomic segments of the virus, revealed a novel characteristic of EHDV2-Ibaraki infection: an uncharacteristically low fold increase in titer upon infection of different cell models. To address the function and regulation of NS3 we employed the following approaches: (i) development (together with Anima Cell Metrology) of a novel technique (based on the transfection of fluorescently-labeledtRNAs) that allows for the detection of the levels of synthesis of individual viral proteins (i.e. NS3) in single cells; (ii) development of a siRNA-mediated knockdown approach for the reduction in levels of expression of NS3 in EHDV2-Ibaraki infected cells; (iii) biochemical and microscopy-based analysis of the localization, levels and post-translational modifications of NS3 in infected cells. In addition, we identified the altered regulation and spatial compartmentalization of protein synthesis in cells infected with EHDV2-Ibaraki or the mammalian reovirus. In EHDV2-Ibaraki-infected cells such altered regulation in protein synthesis occurs in the context of a cell stress reponse that includes the induction of apoptosis, autophagy and activation of the stressrelated kinase c-Jun N-terminal Kinase (JNK). Interestingly, inhibition of such stress-related cellular processes diminishes the production of infectious virions, suggesting that EHDV usurps these responses for the benefit of efficient infection. Taken together, while the present project fell short of the generation of novel reverse genetics systems for orbiviruses, the development of novel experimental approaches and techniques, and their employment in the analysis of EHDV-infected cells, yielded novel insights in the interactions of orbiviruses with mammalian cells.
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Eldar, Avigdor, and Donald L. Evans. Streptococcus iniae Infections in Trout and Tilapia: Host-Pathogen Interactions, the Immune Response Toward the Pathogen and Vaccine Formulation. United States Department of Agriculture, December 2000. http://dx.doi.org/10.32747/2000.7575286.bard.
Повний текст джерелаАнотація:
In Israel and in the U.S., Streptococcus iniae is responsible for considerable losses in various fish species. Poor understanding of its virulence factors and limited know-how-to of vaccine formulation and administration are the main reasons for the limited efficacy of vaccines. Our strategy was that in order to Improve control measures, both aspects should be equally addressed. Our proposal included the following objectives: (i) construction of host-pathogen interaction models; (ii) characterization of virulence factors and immunodominant antigens, with assessment of their relative importance in terms of protection and (iii) genetic identification of virulence factors and genes, with evaluation of the protective effect of recombinant proteins. We have shown that two different serotypes are involved. Their capsular polysaccharides (CPS) were characterized, and proved to play an important role in immune evasion and in other consequences of the infection. This is an innovative finding in fish bacteriology and resembles what, in other fields, has become apparent in the recent years: S. iniae alters surface antigens. By so doing, the pathogen escapes immune destruction. Immunological assays (agar-gel immunodiffusion and antibody titers) confirmed that only limited cross recognition between the two types occurs and that capsular polysaccharides are immunodominant. Vaccination with purified CPS (as an acellular vaccine) results in protection. In vitro and ex-vivo models have allowed us to unravel additional insights of the host-pathogen interactions. S. iniae 173 (type II) produced DNA fragmentation of TMB-8 cells characteristic of cellular necrosis; the same isolate also prevented the development of apoptosis in NCC. This was determined by finding reduced expression of phosphotidylserine (PS) on the outer membrane leaflet of NCC. NCC treated with this isolate had very high levels of cellular necrosis compared to all other isolates. This cellular pathology was confirmed by observing reduced DNA laddering in these same treated cells. Transmission EM also showed characteristic necrotic cellular changes in treated cells. To determine if the (in vitro) PCD/apoptosis protective effects of #173 correlated with any in vivo activity, tilapia were injected IV with #173 and #164 (an Israeli type I strain). Following injection, purified NCC were tested (in vitro) for cytotoxicity against HL-60 target cells. Four significant observations were made : (i) fish injected with #173 had 100-400% increased cytotoxicity compared to #164 (ii) in vivo activation occurred within 5 minutes of injection; (iii) activation occurred only within the peripheral blood compartment; and (iv) the isolate that protected NCC from apoptosis in vitro caused in vivo activation of cytotoxicity. The levels of in vivo cytotoxicity responses are associated with certain pathogens (pathogen associated molecular patterns/PAMP) and with the tissue of origin of NCC. NCC from different tissue (i.e. PBL, anterior kidney, spleen) exist in different states of differentiation. Random amplified polymorphic DNA (RAPD) analysis revealed the "adaptation" of the bacterium to the vaccinated environment, suggesting a "Darwinian-like" evolution of any bacterium. Due to the selective pressure which has occurred in the vaccinated environment, type II strains, able to evade the protective response elicited by the vaccine, have evolved from type I strains. The increased virulence through the appropriation of a novel antigenic composition conforms with pathogenic mechanisms described for other streptococci. Vaccine efficacy was improved: water-in-oil formulations were found effective in inducing protection that lasted for a period of (at least) 6 months. Protection was evaluated by functional tests - the protective effect, and immunological parameters - elicitation of T- and B-cells proliferation. Vaccinated fish were found to be resistant to the disease for (at least) six months; protection was accompanied by activation of the cellular and the humoral branches.
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Malkinson, Mertyn, Irit Davidson, Moshe Kotler, and Richard L. Witter. Epidemiology of Avian Leukosis Virus-subtype J Infection in Broiler Breeder Flocks of Poultry and its Eradication from Pedigree Breeding Stock. United States Department of Agriculture, March 2003. http://dx.doi.org/10.32747/2003.7586459.bard.
Повний текст джерелаАнотація:
Objectives 1. Establish diagnostic procedures to identify tolerant carrier birds based on a) Isolation of ALV-J from blood, b) Detection of group-specific antigen in cloacal swabs and egg albumen. Application of these procedures to broiler breeder flocks with the purpose of removing virus positive birds from the breeding program. 2. Survey the AL V-J infection status of foundation lines to estimate the feasibility of the eradication program 3. Investigate virus transmission through the embryonated egg (vertical) and between chicks in the early post-hatch period (horizontal). Establish a model for limiting horizontal spread by analyzing parameters operative in the hatchery and brooder house. 4. Compare the pathogenicity of AL V-J isolates for broiler chickens. 5. Determine whether AL V-J poses a human health hazard by examining its replication in mammalian and human cells. Revisions. The: eradication objective had to be terminated in the second year following the closing down of the Poultry Breeders Union (PBU) in Israel. This meant that their foundation flocks ceased to be available for selection. Instead, the following topics were investigated: a) Comparison of commercial breeding flocks with and without myeloid leukosis (matched controls) for viremia and serum antibody levels. b) Pathogenicity of Israeli isolates for turkey poults. c) Improvement of a diagnostic ELISA kit for measuring ALV-J antibodies Background. ALV-J, a novel subgroup of the avian leukosis virus family, was first isolated in 1988 from broiler breeders presenting myeloid leukosis (ML). The extent of its spread among commercial breeding flocks was not appreciated until the disease appeared in the USA in 1994 when it affected several major breeding companies almost simultaneously. In Israel, ML was diagnosed in 1996 and was traced to grandparent flocks imported in 1994-5, and by 1997-8, ML was present in one third of the commercial breeding flocks It was then realized that ALV-J transmission was following a similar pattern to that of other exogenous ALVs but because of its unusual genetic composition, the virus was able to establish an extended tolerant state in infected birds. Although losses from ML in affected flocks were somewhat higher than normal, both immunosuppression and depressed growth rates were encountered in affected broiler flocks and affected their profitability. Conclusions. As a result of the contraction in the number of international primary broiler breeders and exchange of male and female lines among them, ALV-J contamination of broiler breeder flocks affected the broiler industry worldwide within a short time span. The Israeli national breeding company (PBU) played out this scenario and presented us with an opportunity to apply existing information to contain the virus. This BARD project, based on the Israeli experience and with the aid of the ADOL collaborative effort, has managed to offer solutions for identifying and eliminating infected birds based on exhaustive virological and serological tests. The analysis of factors that determine the efficiency of horizontal transmission of virus in the hatchery resulted in the workable solution of raising young chicks in small groups through the brooder period. These results were made available to primary breeders as a strategy for reducing viral transmission. Based on phylogenetic analysis of selected Israeli ALV-J isolates, these could be divided into two groups that reflected the countries of origin of the grandparent stock. Implications. The availability of a simple and reliable means of screening day old chicks for vertical transmission is highly desirable in countries that rely on imported breeding stock for their broiler industry. The possibility that AL V-J may be transmitted to human consumers of broiler meat was discounted experimentally.
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Chejanovsky, Nor, and Bruce A. Webb. Potentiation of Pest Control by Insect Immunosuppression. United States Department of Agriculture, January 2010. http://dx.doi.org/10.32747/2010.7592113.bard.
Повний текст джерелаАнотація:
The restricted host range of many baculoviruses, highly pathogenic to Lepidoptera and non-pathogenic to mammals, limits their use to single or few closely related Lepidopteran species and is an obstacle to extending their implementation for pest control. The insect immune response is a major determinant of the ability of an insect pathogen to efficiently multiply and propagate. We have developed an original model system to study the Lepidopteran antiviral immune response based on Spodoptera littoralis resistance to AcMNPV (Autographa californica multiple nucleopolyhedrovirus) infection and the fascinating immunosuppressive activity of polydnaviruses .Our aim is to elucidate the mechanisms through which the immunosuppressive insect polydnaviruses promote replication of pathogenic baculoviruses in lepidopteran hosts that are mildly or non-permissive to virus- replication. In this study we : 1- Assessed the extent to which and the mechanisms whereby the immunosuppressive Campoletis sonorensis polydnavirus (CsV) or its genes enhanced replication of a well-characterized pathogenic baculovirus AcMNPV, in polydnavirus-immunosuppressedH. zea and S. littoralis insects and S. littoralis cells, hosts that are mildly or non-permissive to AcMNPV. 2- Identified CsV genes involved in the above immunosuppression (e.g. inhibiting cellular encapsulation and disrupting humoral immunity). We showed that: 1. S. littoralis larvae mount an immune response against a baculovirus infection. 2. Immunosuppression of an insect pest improves the ability of a viral pathogen, the baculovirus AcMNPV, to infect the pest. 3. For the first time two PDV-specific genes of the vankyrin and cystein rich-motif families involved in immunosuppression of the host, namely Pvank1 and Hv1.1 respectively, enhanced the efficacy of an insect pathogen toward a semipermissive pest. 4. Pvank1 inhibits apoptosis of Spodopteran cells elucidating one functional aspect of PDVvankyrins. 5. That Pvank-1 and Hv1.1 do not show cooperative effect in S. littoralis when co-expressed during AcMNPV infection. Our results pave the way to developing novel means for pest control, including baculoviruses, that rely upon suppressing host immune systems by strategically weakening insect defenses to improve pathogen (i.e. biocontrol agent) infection and virulence. Also, we expect that the above result will help to develop systems for enhanced insect control that may ultimately help to reduce transmission of insect vectored diseases of humans, animals and plants as well as provide mechanisms for suppression of insect populations that damage crop plants by direct feeding.
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Stern, David, and Gadi Schuster. Manipulation of Gene Expression in the Chloroplast. United States Department of Agriculture, September 2000. http://dx.doi.org/10.32747/2000.7575289.bard.
Повний текст джерелаАнотація:
The steady-state level of a given mRNA is determined by its rates of transcription and degradation. The stabilities of chloroplast mRNAs vary during plant development, in part regulating gene expression. Furthermore, the fitness of the organelle depends on its ability to destroy non-functional transcripts. In addition, there is a resurgent interest by the biotechnology community in chloroplast transformation due to the public concerns over pollen transmission of introduced traits or foreign proteins. Therefore, studies into basic gene expression mechanisms in the chloroplast will open the door to take advantage of these opportunities. This project was aimed at gaining mechanistic insights into mRNA processing and degradation in the chloroplast and to engineer transcripts of varying stability in Chlamydomonas reinhardtii cells. This research uncovered new and important information on chloroplast mRNA stability, processing, degradation and translation. In particular, the processing of the 3' untranslated regions of chloroplast mRNAs was shown to be important determinants in translation. The endonucleolytic site in the 3' untranslated region was characterized by site directed mutagensis. RNA polyadenylation has been characterized in the chloroplast of Chlamydomonas reinhardtii and chloroplast transformants carrying polyadenylated sequences were constructed and analyzed. Data obtained to date suggest that chloroplasts have gene regulatory mechanisms which are uniquely adapted to their post-endosymbiotic environment, including those that regulate RNA stability. An exciting point has been reached, because molecular genetic studies have defined critical RNA-protein interactions that participate in these processes. However, much remains to be learned about these multiple pathways, how they interact with each other, and how many nuclear genes are consecrated to overseeing them. Chlamydomonas is an ideal model system to extend our understanding of these areas, given its ease of manipulation and the existing knowledge base, some of which we have generated.
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Rousseau, Henri-Paul. Gutenberg, L’université et le défi numérique. CIRANO, December 2022. http://dx.doi.org/10.54932/wodt6646.
Повний текст джерелаАнотація:
Introduction u cours des deux derniers millénaires, il y a eu plusieurs façons de conserver, transmettre et même créer la connaissance ; la tradition orale, l’écrit manuscrit, l’écrit imprimé et l’écrit numérisé. La tradition orale et le manuscrit ont dominé pendant plus de 1400 ans, et ce, jusqu’à l’apparition du livre imprimé en 1451, résultant de l’invention mécanique de Gutenberg. Il faudra attendre un peu plus de 550 ans, avant que l’invention du support électronique déloge à son tour le livre imprimé, prenant une ampleur sans précédent grâce à la révolution numérique contemporaine, résultat du maillage des technologies de l’informatique, de la robotique et de la science des données. Les premières universités qui sont nées en Occident, au Moyen Âge, ont développé cette tradition orale de la connaissance tout en multipliant l’usage du manuscrit créant ainsi de véritables communautés de maîtres et d’étudiants ; la venue de l’imprimerie permettra la multiplication des universités où l’oral et l’écrit continueront de jouer un rôle déterminant dans la création et la transmission des connaissances même si le « support » a évolué du manuscrit à l’imprimé puis vers le numérique. Au cours de toutes ces années, le modèle de l’université s’est raffiné et perfectionné sur une trajectoire somme toute assez linéaire en élargissant son rôle dans l’éducation à celui-ci de la recherche et de l’innovation, en multipliant les disciplines offertes et les clientèles desservies. L’université de chaque ville universitaire est devenue une institution florissante et indispensable à son rayonnement international, à un point tel que l’on mesure souvent sa contribution par la taille de sa clientèle étudiante, l’empreinte de ses campus, la grandeur de ses bibliothèques spécialisées ; c’est toutefois la renommée de ses chercheurs qui consacre la réputation de chaque université au cours de cette longue trajectoire pendant laquelle a pu s’établir la liberté universitaire. « Les libertés universitaires empruntèrent beaucoup aux libertés ecclésiastiques » : Étudiants et maîtres, qu'ils furent, ou non, hommes d'Église, furent assimilés à des clercs relevant de la seule justice ecclésiastique, réputée plus équitable. Mais ils échappèrent aussi largement à la justice ecclésiastique locale, n'étant justiciables que devant leur propre institution les professeurs et le recteur, chef élu de l’université - ou devant le pape ou ses délégués. Les libertés académiques marquèrent donc l’émergence d'un droit propre, qui ménageait aux maîtres et aux étudiants une place à part dans la société. Ce droit était le même, à travers l'Occident, pour tous ceux qui appartenaient à ces institutions supranationales que furent, par essence, les premières universités. À la fin du Moyen Âge, l'affirmation des États nationaux obligea les libertés académiques à s'inscrire dans ce nouveau cadre politique, comme de simples pratiques dérogatoires au droit commun et toujours sujettes à révision. Vestige vénérable de l’antique indépendance et privilège octroyé par le prince, elles eurent donc désormais un statut ambigu » . La révolution numérique viendra fragiliser ce statut. En effet, la révolution numérique vient bouleverser cette longue trajectoire linéaire de l’université en lui enlevant son quasi monopole dans la conservation et le partage du savoir parce qu’elle rend plus facile et somme toute, moins coûteux l’accès à l’information, au savoir et aux données. Le numérique est révolutionnaire comme l’était l’imprimé et son influence sur l’université, sera tout aussi considérable, car cette révolution impacte radicalement tous les secteurs de l’économie en accélérant la robotisation et la numérisation des processus de création, de fabrication et de distribution des biens et des services. Ces innovations utilisent la radio-identification (RFID) qui permet de mémoriser et de récupérer à distance des données sur les objets et l’Internet des objets qui permet aux objets d’être reliés automatiquement à des réseaux de communications .Ces innovations s’entrecroisent aux technologies de la réalité virtuelle, à celles des algorithmiques intelligentes et de l’intelligence artificielle et viennent littéralement inonder de données les institutions et les organisations qui doivent alors les analyser, les gérer et les protéger. Le monde numérique est né et avec lui, a surgi toute une série de compétences radicalement nouvelles que les étudiants, les enseignants et les chercheurs de nos universités doivent rapidement maîtriser pour évoluer dans ce Nouveau Monde, y travailler et contribuer à la rendre plus humain et plus équitable. En effet, tous les secteurs de l’activité commerciale, économique, culturelle ou sociale exigent déjà clairement des connaissances et des compétences numériques et technologiques de tous les participants au marché du travail. Dans cette nouvelle logique industrielle du monde numérique, les gagnants sont déjà bien identifiés. Ce sont les fameux GAFAM (Google, Apple, Facebook, Amazon et Microsoft) suivis de près par les NATU (Netflix, Airbnb, Tesla et Uber) et par les géants chinois du numérique, les BATX (Baidu, Alibaba, Tenant et Xiaomi). Ces géants sont alimentés par les recherches, les innovations et les applications mobiles (APPs) créées par les partenaires de leurs écosystèmes regroupant, sur différents campus d’entreprises, plusieurs des cerveaux qui sont au cœur de cette révolution numérique. L’université voit donc remise en question sa capacité traditionnelle d’attirer, de retenir et de promouvoir les artisans du monde de demain. Son aptitude à former des esprits critiques et à contribuer à la transmission des valeurs universelles est également ébranlée par ce tsunami de changements. Il faut cependant reconnaître que les facultés de médecine, d’ingénierie et de sciences naturelles aux États-Unis qui ont développé des contacts étroits, abondants et suivis avec les hôpitaux, les grandes entreprises et l’administration publique et cela dès la fin du 19e siècle ont été plus en mesure que bien d’autres, de recruter et retenir les gens de talent. Elle ont énormément contribué à faire avancer les connaissances scientifiques et la scolarisation en sciences appliquées ..La concentration inouïe des Prix Nobel scientifiques aux États-Unis est à cet égard très convaincante . La révolution numérique contemporaine survient également au moment même où de grands bouleversements frappent la planète : l’urgence climatique, le vieillissement des populations, la « déglobalisation », les déplacements des populations, les guerres, les pandémies, la crise des inégalités, de l’éthique et des démocraties. Ces bouleversements interpellent les universitaires et c’est pourquoi leur communauté doit adopter une raison d’être et ainsi renouveler leur mission afin des mieux répondre à ces enjeux de la civilisation. Cette communauté doit non seulement se doter d’une vision et des modes de fonctionnement adaptés aux nouvelles réalités liées aux technologies numériques, mais elle doit aussi tenir compte de ces grands bouleversements. Tout ceci l’oblige à s’intégrer à des écosystèmes où les connaissances sont partagées et où de nouvelles compétences doivent être rapidement acquises. Le but de ce texte est de mieux cerner l’ampleur du défi que pose le monde numérique au milieu universitaire et de proposer quelques idées pouvant alimenter la réflexion des universitaires dans cette démarche d’adaptation au monde numérique. Or, ma conviction la plus profonde c’est que la révolution numérique aura des impacts sur nos sociétés et notre civilisation aussi grands que ceux provoqués par la découverte de l’imprimerie et son industrialisation au 15e siècle. C’est pourquoi la première section de ce document est consacrée à un rappel historique de la révolution de l’imprimerie par Gutenberg alors que la deuxième section illustrera comment les caractéristiques de la révolution numérique viennent soutenir cette conviction si profonde. Une troisième section fournira plus de détails sur le défi d’adaptation que le monde numérique pose aux universités alors que la quatrième section évoquera les contours du changement de paradigme que cette adaptation va imposer. La cinquième section servira à illustrer un scénario de rêves qui permettra de mieux illustrer l’ampleur de la gestion du changement qui guette les universitaires. La conclusion permettra de revenir sur quelques concepts et principes clefs pour guider la démarche vers l’action. L’université ne peut plus « être en haut et seule », elle doit être « au centre et avec » des écosystèmes de partenariats multiples, dans un modèle hybride physique/virtuel. C’est ainsi qu’elle pourra conserver son leadership historique de vigie du savoir et des connaissances d’un monde complexe, continuer d’établir l’authenticité des faits et imposer la nécessaire rigueur de la science et de l’objectivité.