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Auswahl der wissenschaftlichen Literatur zum Thema „Electron-component“
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Zeitschriftenartikel zum Thema "Electron-component"
1
Dubas, L. G. „Single-component relativistic electron flux“. Technical Physics Letters 32, Nr. 6 (Juni 2006): 527–28. http://dx.doi.org/10.1134/s106378500606023x.
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2
Syrovoi, V. A. „Theory of single-component electron beams“. Radiophysics and Quantum Electronics 33, Nr. 6 (Juni 1990): 546–53. http://dx.doi.org/10.1007/bf01037861.
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3
Grimme, Stefan, Lars Goerigk und Reinhold F. Fink. „Spin-component-scaled electron correlation methods“. Wiley Interdisciplinary Reviews: Computational Molecular Science 2, Nr. 6 (22.06.2012): 886–906. http://dx.doi.org/10.1002/wcms.1110.
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Bharuthram, R., S. S. Misthry und M. Y. Yu. „Electron acoustic surface waves in a two‐electron component plasma“. Physics of Fluids B: Plasma Physics 5, Nr. 12 (Dezember 1993): 4502–4. http://dx.doi.org/10.1063/1.860567.
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5
McKENZIE, J. F. „Electron acoustic–Langmuir solitons in a two-component electron plasma“. Journal of Plasma Physics 69, Nr. 3 (April 2003): 199–210. http://dx.doi.org/10.1017/s002237780300206x.
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We investigate the conditions under which ‘high-frequency’ electron acoustic–Langmuir solitons can be constructed in a plasma consisting of protons and two electron populations: one ‘cold’ and the other ‘hot’. Conservation of total momentum can be cast as a structure equation either for the ‘cold’ or ‘hot’ electron flow speed in a stationary wave using the Bernoulli energy equations for each species. The linearized version of the governing equations gives the dispersion equation for the stationary waves of the system, from which follows the necessary – but not sufficient – conditions for the existence of soliton structures; namely that the wave speed must be less than the acoustic speed of the ‘hot’ electron component and greater than the low-frequency compound acoustic speed of the two electron populations. In this wave speed regime linear waves are ‘evanescent’, giving rise to the exponential growth or decay, which readily can give rise to non-linear effects that may balance dispersion and allow soliton formation. In general the ‘hot’ component must be more abundant than the ‘cold’ one and the wave is characterized by a compression of the ‘cold’ component and an expansion in the ‘hot’ component necessitating a potential dip. Both components are driven towards their sonic points; the ‘cold’ from above and the ‘hot’ from below. It is this transonic feature which limits the amplitude of the soliton. If the ‘hot’ component is not sufficiently abundant the window for soliton formation shrinks to a narrow speed regime which is quasi-transonic relative to the ‘hot’ electron acoustic speed, and it is shown that smooth solitons cannot be constructed. In the special case of a very cold electron population (i.e. ‘highly supersonic’) and the other population being very hot (i.e. ‘highly subsonic’) with adiabatic index 2, the structure equation simplifies and can be integrated in terms of elementary transcendental functions that provide the fully non-linear counterpart to the weakly non-linear sech$^{2}$-type solitons. In this case the limiting soliton is comprised of an infinite compression in the cold component, a weak rarefaction in the ‘hot’ electrons and a modest potential dip.
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Mace, R. L., S. Baboolal, R. Bharuthram und M. A. Hellberg. „Arbitrary-amplitude electron-acoustic solitons in a two-electron-component plasma“. Journal of Plasma Physics 45, Nr. 3 (Juni 1991): 323–38. http://dx.doi.org/10.1017/s0022377800015749.
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Motivated by plasma and wave measurements in the cusp auroral region, we have investigated electron-acoustic solitons in a plasma consisting of fluid ions, a cool fluid electron and a hot Boltzmann electron component. A recently described method of integrating the full nonlinear fluid equations as an initial-value problem is used to construct electron-acoustic solitons of arbitrary amplitude. Using the reductive perturbation technique, a Korteweg-de Vries equation, which includes the effects of finite cool-electron and ion temperatures, is derived, and results are compared with the full theory. Both theories admit rarefactive soliton solutions only. The solitons are found to propagate at speeds greater than the electron sound speed (ε0c/ε0ε)½υε, and their profiles are independent of ion parameters. It is found that the KdV theory is not a good approximation for intermediate-strength solitons. Nor does it exhibit the fact that the cool- to hot-electron temperature ratio restricts the parameter range over which electron-acoustic solitons may exist, as found in the arbitrary-amplitude calculations.
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Khrapak, S. A., und G. Morfill. „Waves in two component electron-dust plasma“. Physics of Plasmas 8, Nr. 6 (Juni 2001): 2629–34. http://dx.doi.org/10.1063/1.1370061.
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Jiang, N., und J. Silcox. „Electron Irradiation Damage in Multi-Component Glasses“. Microscopy and Microanalysis 6, S2 (August 2000): 390–91. http://dx.doi.org/10.1017/s1431927600034449.
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Understanding electron beam induced damage in glasses, especially in multi-component glasses, is very important, since the interaction of electron probes with glass is a very common approach to determine glass composition and structure. For example, the decay of characteristic X-ray and Auger electron intensities, using electron beams as probes, of alkalis in glasses have been known for years. In addition, both phase separation and formation of gas bubbles in the glasses have also been reported. Many irradiation effects are strongly dependent on the structure, bonding and composition of matter. In general, three types of mechanisms, knock-on damage, ionization and field-induced migration have been introduced to describe the damage induced by electron irradiation. Here, we demonstrate electron irradiation induced phase decomposition in a multi-component oxide glass, and introduce a modified model to interpret the damage process.
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Danehkar, Ashkbiz, Nareshpal Singh Saini, Manfred A. Hellberg und Ioannis Kourakis. „Electron-acoustic solitary waves in the presence of a suprathermal electron component“. Physics of Plasmas 18, Nr. 7 (Juli 2011): 072902. http://dx.doi.org/10.1063/1.3606365.
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Mbuli, L. N., S. K. Maharaj, R. Bharuthram, S. V. Singh und G. S. Lakhina. „Arbitrary amplitude fast electron-acoustic solitons in three-electron component space plasmas“. Physics of Plasmas 23, Nr. 6 (Juni 2016): 062302. http://dx.doi.org/10.1063/1.4952637.
Der volle Inhalt der QuelleDissertationen zum Thema "Electron-component"
1
Malins, Andrew E. R. „The development of a three-component electron spin polarimeter“. Thesis, Loughborough University, 2000. https://dspace.lboro.ac.uk/2134/33190.
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The thesis is primarily concerned with the design, construction and preliminary commissioning of a novel polarimeter for full three-dimensional analysis of electron spin polarisation. The polarimeter is described in detail, together with the theoretical basis for its operation. Studies of an amorphous ferromagnetic alloy, Co66Fe4Ni1B14Si15, and its application as a secondary standard are presented. Finally, a design study of a GaAs polarised electron source, capable of providing both longitudinal and transverse polarisations, is detailed.
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Lin, Tzong-Yuan. „Electron transfer between the reductase and ferredoxin component of toluene dioxygenase“. Doctoral thesis, Humboldt-Universität zu Berlin, Mathematisch-Naturwissenschaftliche Fakultät I, 2012. http://dx.doi.org/10.18452/16584.
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Die Toluol-Dioxygenase von Pseudomonas putida F1 ist eine Rieske-Dioxygenase und besteht aus Reduktase-, Ferredoxin- und Oxygenase-Komponente. Sie katalysiert den ersten Schritt im aeroben Abbau von Toluol. Ein effizienter Elektronentransfer zur terminalen Oxygenase-Komponente - an der die Sauerstoffaktivierung und Umwandlung von Toluol zum cis-Toluol-Dihydrodiol stattfindet - setzt eine reibungslose Interaktion aller Komponenten voraus. Die Ergebnisse der Stopped-flow-Messungen in der reduktiven Halbreaktion zeigen, dass NADH die Reduktase mittels Hydridtransfer reduziert, wodurch ein stabiler Ladungstransfer-Komplex zwischen NAD+ und FADH- entsteht. In der oxidativen Halbreaktion wird dieser dann durch einen Elektronenakzeptor über das blaue Semichinon zum Chinon oxidiert. Dabei zeigt sich, dass der Ladungstransfer-Komplex die Reaktion der Reduktase mit Sauerstoff unterdrückt. Eine Erklärung hierfür liefert die Kristallstruktur des Ladungstransfer-Komplexes. Die Reaktion mit Sauerstoff wird dadurch unterdrückt, dass das NAD+ koplanar mit dem Isoalloxazinring ist und den reaktiven N5-C4a Teil des FADs schützt und zudem den Isoalloxazinring in eine planare, weniger sauerstoffempfindliche Konformation zwängt. Durch die Bildung des Reduktase-Ferredoxin-Komplexes wird ein effizienter Elektronentransfer folgendermaßen ermöglicht: a) das Ferredoxin bindet an die Reduktase aufgrund elektrostatischer Anziehung entgegengesetzter Oberflächenladungen beider Proteine, b) die hydrophobe Region, die die beiden Redoxzentren umgibt, fungiert als Ein- und Ausgang für Elektronen und c) die geringe Entfernung von 11.7 Å zwischen beiden Kofaktoren erlaubt einen schnellen Elektronentransfer. Die Ergebnisse dieser Arbeit zeigen, dass der Elektronentransfer zwischen Reduktase und Ferredoxin durch die Bildung eines stabilen Ladungstransfer- und Reduktase- Ferredoxin-Komplexes beeinflusst wird und dadurch das Problem einer ungewollten Reaktion mit Sauerstoff umgangen wird.The toluene dioxygenase from Pseudomonas putida F1 is a three-component Rieske non-heme iron dioxygenase comprising of a reductase, ferredoxin and an oxygenase component. It catalyzes the initial step in the aerobic degradation of toluene to cis-toluene dihydrodiol. A smooth interaction between all three components needs to be ensured to efficiently transfer the electrons derived from NADH oxidation to the terminal oxygenase component where molecular oxygen is activated and used for the hydroxylation of toluene. The results of the kinetic studies of the reductive half reaction of reductase reveal that NADH reduces the reductase, resulting in the formation of a stable charge transfer complex between NAD+ and FADH-. Oxidation of the charge transfer complex by an electron acceptor proceeds via the neutral semiquinone to the quinone state of FAD. It is shown that the charge transfer complex suppresses the reaction of the reductase with dioxygen. An explanation for this change in reactivity can be deduced from the structure of the charge transfer complex. Its slower reaction with dioxygen results from NAD+ lying coplanar with the FAD shielding its reactive N5-C4a locus and the forced planarity of the isoalloxazine ring. The formation of the reductase-ferredoxin complex allows efficient electron transfer from reductase to ferredoxin because a) the oppositely charged interacting surfaces of both proteins facilitate the pre-orientation of the ferredoxin on the reductase, b) a hydrophobic region surrounding the two redox centers in the complex acts as an exit/entrance port for electrons and c) the short edge-to-edge distance between both cofactors of 11.7 Å guarantees a fast electron transfer. The results demonstrate that the electron transfer between reductase and ferredoxin is governed by the formation of a stable charge transfer and of a reductase-ferredoxin complex with which the problem of an unwanted side reaction with dioxygen is obviated.
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Dronov, Roman. „Multi-component protein films by layer-by-layer : assembly and electron transfer“. Phd thesis, Universität Potsdam, 2007. http://opus.kobv.de/ubp/volltexte/2008/1728/.
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Electron transfer phenomena in proteins represent one of the most common types of biochemical reactions. They play a central role in energy conversion pathways in living cells, and are crucial components in respiration and photosynthesis. These complex biochemical reaction cascades consist of a series of proteins and protein complexes that couple a charge transfer to different forms of chemical energy. The efficiency and sophisticated optimisation of signal transfer in these natural redox chains has inspired engineering of artificial architectures mimicking essential properties of their natural analogues.
Implementation of direct electron transfer (DET) in protein assemblies was a breakthrough in bioelectronics, providing a simple and efficient way for coupling biological recognition events to a signal transducer. DET avoids the use of redox mediators, reducing potential interferences and side reactions, as well as being more compatible with in vivo conditions. However, only a few haem proteins, including the redox protein cytochrome c (cyt.c), and blue copper enzymes show efficient DET on different kinds of electrodes.
Previous investigations with cyt.c have mainly focused on heterogeneous electron transfer of monolayers of this protein on gold. An important advance was the fabrication of cyt.c multilayers by electrostatic layer-by-layer self-assembly. The ease of fabrication, the stability, and the controllable permeability of polyelectrolyte multilayers have made them particularly attractive for electroanalytical applications. With cyt.c and sulfonated polyaniline it was for the first time possible that fully electro-active multilayers of the redox protein could be prepared.
This approach was extended to design an analytical signal chain based on multilayers of cyt.c and xanthine oxidase (XOD). The system does not need an external mediator but relies on an in situ generation of a mediating radical and thus allows a signal transfer from hypoxanthine via the substrate converting enzyme and cyt.c to the electrode.
Another kind of a signal chain is based on assembling proteins in complexes on electrodes in such a way that a direct protein-protein electron transfer becomes feasible. This design does not need a redox mediator in analogy to natural protein communication. For this purpose, cyt.c and the enzyme bilirubin oxidase (BOD, EC 1.3.3.5) are co-immobilized in a self-assembled polyelectrolyte multilayer on gold electrodes. Although these two proteins are not natural reaction partners, the protein architecture facilitates an electron transfer from the electrode via multiple protein layers to molecular oxygen resulting in a significant catalytic reduction current.
Finally, we describe a novel strategy for multi-protein layer-by-layer self-assembly combining cyt.c with an enzyme sulfite oxidase (SOx) without use of any additional polymer. Electrostatic interactions between these two proteins with rather separated pI values during the assembly process from a low ionic strength buffer were found sufficient for the layer-by-layer deposition of the both biomolecules.
It is anticipated that the concepts described in this work will stimulate further progress in multilayer design of even more complex biomimetic signal cascades taking advantage of direct communication between proteins.Elektronentransferphänomene in Proteinen stellen den häufigsten Typ biochemischer Reaktionen dar. Sie spielen eine zentrale Rolle bei der Energieumwandlung in der Zelle und sind entscheidende Komponenten in der Atmung und Photosynthese. Diese komplexen Kaskaden biochemischer Reaktionen setzen sich aus einer Reihe von Proteinen und Proteinkomplexen zusammen, die den Energietransfer an verschiedene Formen chemischer Energie koppeln. Die große Effektivität und Selektivität des Signaltransfers in diesen natürlichen Redoxketten war Vorbild für die Entwicklung künstlicher Architekturen, die die wesentlichen Eigenschaften ihrer natürlichen Analoga nachahmen. Die Implementierung des direkten Elektronentransfers (DET) von Proteinen mit Elektroden war ein Durchbruch im Bereich der Bioelektronik. Sie lieferte einen einfachen und effizienten Weg für das Koppeln biologischer Erkennungsereignisse an einen Signalumwandler. Durch den DET können Redoxmediatoren vermieden und damit potentielle Grenzflächen und Nebenreaktionen reduziert werden. Ebenso wird damit die Kompatibilität für in vivo Bedingungen erhöht. Jedoch zeigen nur einige Hämproteine wie das Redoxprotein Cytochrom c (Cyt c) und blaue Kupferproteine einen effizienten DET auf verschiedenen Elektrodentypen. Bisherige Untersuchungen mit Cyt c konzentrierten sich hauptsächlich auf den heterogenen Elektronentransfer von Monoschichten dieses Proteins auf Gold. Ein wichtiger Fortschritt war die Herstellung von Cyt c Multischichten durch die elektrostatische Layer-by-Layer-Technik. Die einfache Herstellung, die Stabilität sowie die kontrollierbaren Permeationseigenschaften von Polyelektrolyt-Multischichten machte sie besonders attraktiv für elektroanalytische Anwendungen. So gelang es auch zum ersten Mal vollständig elektroaktive Multischichten aus Cyt c und Polyanilinsulfonsäure zu präparieren. Dieser Ansatz wurde hier erweitert, um eine analytische Signalkette auf der Basis von Multischichten aus Cyt c und Xanthinoxidase zu entwerfen. Das System bedarf keinen externen Mediator, es hängt jedoch von der in situ Generierung eines vermittelnden Radikals ab und erlaubt daher einen Signaltransfer von Hypoxanthin über ein substratumwandelndes Enzym und Cyt c zur Elektrode. Eine andere Art von Signalketten basiert auf der Assemblierung von Proteinen in Komplexen auf Elektroden in solcher Art und Weise, daß ein direkter Protein-Protein-Elektronentransfer möglich wird. Dieser Ansatz benötigt keinen Redoxmediator in Analogie zu Beispielen aus dem biologischen Signaltransfer. Zu diesem Zweck werden Cyt c und das Enzym Bilirubinoxidase mit einem selbst-assemblierenden Polyelektrolyten auf einer Goldelektrode koimmobilisiert. Obwohl diese zwei Proteine keine natürlichen Reaktionspartner sind, unterstützt die Protein-Architektur einen Elektronentransfer von der Elektrode über mehrere Proteinschichten zu molekularem Sauerstoff und ergibt einen signifikanten katalytischen Reduktionsstrom. Schließlich wird eine neue Strategie beschrieben für eine Selbstassemblierung von Proteinen ohne zusätzlichen Polyelektrolyten - am Beispiel der Kombination von Cyt c mit Sulfitoxidase. Es stellte sich heraus, daß die elektrostatische Wechselwirkung zwischen diesen zwei Proteinen mit ziemlich weit voneinander entfernt liegenden pI-Werten während des Assemblierungsprozesses durch einen Puffer mit geringer Ionenstärke ausreicht um die beiden Biomoleküle nach dem Layer-by-Layer-Prinzip auf einer Elektrode abzuscheiden. Es wird erwartet, daß das entwickelte Konzept von Multiprotein-Assemblaten auf Elektroden weitere Fortschritte bei dem Entwurf von Multischichten und sogar noch komplexeren biomimetischen Signalkaskaden anregen wird und dabei der Vorteil der direkten Kommunikation zwischen Proteinen genutzt wird.
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Caravaca, Rodríguez Javier. „Measurement of the electron-neutrino component of the T2K beam and search for electron-neutrino disappearance at the T2K Near Detector“. Doctoral thesis, Universitat Autònoma de Barcelona, 2014. http://hdl.handle.net/10803/283399.
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T2K es un experimento de oscilaciones de neutrinos de largo recorrido en el que por primera vez se
ha observado la aparición de neutrinos electrónicos en un haz de neutrinos muónicos. Así pues, el único ángulo de mezcla que quedaba por conocer, q13, es medido con gran precisión. el background principal de esta medida es la contaminación de neutrinos electrónicos producida en el haz junto con la componente de neutrinos muónicos. Ésta es una componente irreducible que ha de ser medida y controlada.
La componente intrínseca de neutrinos electrónicos es medida antes de las oscilaciones en el detector cercano de T2K confirmando la predicción de la simulación con un precisión del 10%. Se establece que el background de neutrinos electrónicos está bien reproducido y que la principal medida del experimento T2K es exacta.
Por otro lado, estudiar la componente de neutrinos electrónicos es interesante para investigar el comportamiento anómalo de algunos experimentos. Estudios en reactores nucleares y resultados en la calibración de experimentos de neutrinos solares con Galio han observado un déficit de neutrinos electrónicos a cortas distancias de la fuente. Este déficit no es compatible con oscilaciones de neutrinos estándar, pero puede ser conciliado en el marco de las oscilaciones, mediante la introducción de un cuarto neutrino con una masa del orden de 1eV². Este nuevo neutrino no sentiría ninguna fuerza del Modelo Estándar y por ello es comúnmente llamado neutrino estéril. Asumiendo que se mezcla con los neutrinos de tipo electrónico, explicaría la desaparición a cortas distancias de los mismos. El detector cercano de T2K se encuentra a una distancia de la fuente óptima para el estudio de oscilaciones de neutrinos estériles ligeros. El modelo más simple de neutrinos estériles con un sólo neutrino adicional es investigado, definiendo intervalos de confianza para los parámetros de oscilación y comparándolos con la literatura.The T2K experiment is a long baseline neutrino experiment that has observed for first time the appearance of electron-neutrinos in a muon-neutrino beam. Thanks to this analysis, the last unknown neutrino mixing angle q13 is measured with a good precision. The main background to this measurement is the contamination of electron-neutrinos produced in the neutrino beam together with the dominant muon-neutrino component. This is an irreducible component that needs to be measured and controlled. The prediction of this component at SuperKamiokande is based on the constrain of the neutrino flux and cross sections by a muon-neutrino selection at the T2K near detector ND280. To confirm this prediction, we measure the electron-neutrino event rates at ND280 before the oscillations occur, establishing that the electron-neutrino component is correctly reproduced by the simulation at the 10% level. In addition, studying the electron-neutrino component is interesting to investigate the abnormal behaviour of some neutrino experiments. The reactor neutrino experiments as well as the results from calibration with radioactive sources in solar neutrino experiment with gallium have observed a deficit of electron-neutrino at very short distances from the neutrino source. This depletion is not compatible with standard neutrino oscillation, but it can be explained by invoking a fourth neutrino with a mass of the order of 1eV². This neutrino does not feel any force of the Standard Model and hence is called sterile neutrino. Assuming that it mixes with the electron-neutrinos, it would be responsible of the short base-line electron-neutrino disappearance due to neutrino oscillation. The T2K near detector is located at a position short enough to study the light sterile neutrino oscillations. The neutrino model with an additional sterile neutrino apart from the three active species is tested and some constraints to the oscillation parameters are set and compared with the literature.
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Nilsson, Erik, und Daniel Johansson. „Testing and evaluation of component made using electron beam melting and Alloy 718 powder“. Thesis, Mälardalens högskola, Akademin för innovation, design och teknik, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:mdh:diva-35566.
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The aerospace industry is constantly striving to becoming more economical and environmentally friendly. One of many efforts to achieve this is the Lightcam project which in this case is evaluating the use of additive manufacturing in the form of electron beam melting in conjunction with the nickel-based superalloy, Alloy 718. This combination is not fully explored and examined. For this purpose, a demonstrator vane was produced and it was subsequently evaluated in this thesis. The evaluation was performed in as-built condition and was divided in non-destructive testing, evaluation of these methods and metallographic review to confirm the results, and potentially revealing more properties. The non-destructive testing was performed using conventional radiography and computed tomography. Both methods struggled to deliver complete and reliable results, for varying reasons. Radiography could deliver results of the whole vane, but these were impossible to evaluate due to the rough surface created by the electron beam melting process. The computed tomography on the other hand was not affected by the rough surface and produced usable, though not complete, results of the vane. The reason for the computed tomography’s inability to deliver complete results was the material, varying thickness and complex geometry of the vane. As a complement and to verify the results from the non-destructive testing, a metallographic examination was conducted. These tests were conducted with the aim of answering the following three questions: What non-destructive testing methods are suitable to evaluate Alloy 718 components manufactured with electron beam melting? - Neither radiography nor computed tomography are suitable as a sole evaluation method, for various reasons. All surface dependent methods were deemed unsuitable without testing due to the rough surface. What types of defects and in what quantity can they be found in the produced vane? - Defects found are: Porosity and lack of fusion, both found as internal and partially external and in varying sizes. Where are the defects located? - Pores are mainly found in the center of sections modeled to a 3mm thickness. Lack of fusion was found between build layers in all thicknesses. Apart from these results, hardness was found to vary depending on build height, increasing from the bottom towards the top. Microstructure was also found to vary with the build height, but always consisting of either equiaxed or columnar grains.Lightcam
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Whitehead, Leigh. „A measurement of the electron neutrino component of the T2K beam using the near detector“. Thesis, University of Warwick, 2012. http://wrap.warwick.ac.uk/51675/.
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T2K is a long baseline neutrino oscillation experiment located in Japan, with a 295km baseline and peak neutrino energy of 0:6 GeV. It is the first off-axis neutrino experiment where the beam is directed approximately 2.5° away from the detectors in order to produce a narrow-band neutrino beam. The experiment was designed to measure the mixing angle θ13 by measuring the neutrino oscillation process vμ -> ve. This measurement relies on the detection of electrons at the far detector from oscillations, and so it is vital to understand the size of the intrinsic ve component of the beam. A measurement of the intrinsic ve component of the T2K beam was performed using the ND280. An analysis that used all of the data taken by the ND280 from February 2010 until March 2011, a total of 1.09 x 10 20 POT, measured 67.7 +- 12.9(stat) +- 5.2(syst) CC ve interactions. The number of events corresponds to a ratio between data and simulation of 0.983+-0.191(stat)+-0.076(syst) and provides strong evidence that the neutrino flux is well simulated. The simulation from the intrinsic ve measurement was then combined with an analysis of vμ interactions in the ND280 to constrain the neutrino flux uncertainties. An idealised study that considered only statistical and flux systematic uncertainties concluded that the intrinsic ve analysis improved the constraint on the flux uncertainties compared to considering only the ND280 vμ analyses, with the effect most prominent at neutrino energies greater than 1 GeV.
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Malkin, Ondík Irina. „Development, validation, and application of new relativistic methods for all-electron unrestricted two-component calculations of EPR parameters“. [S.l.] : [s.n.], 2006. http://deposit.ddb.de/cgi-bin/dokserv?idn=980973600.
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Giganti, Claudio. „Particule Identification in the T2K TPCs and study of the electron neutrino component in the T2K neutrino beam“. Paris 11, 2010. http://www.theses.fr/2010PA112334.
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Cette thèse est consacrée à la mesure de l'apparition du neutrino électronique avec l'expérience T2K. T2K est une expérience pour la mesure des oscillations de neutrinos installée au Japon. Le faisceau de neutrinos est produit par un accélérateur à JPARC et les neutrinos sont observés avant l'oscillation dans un détecteur proche, ND280, et après l'oscillation dans un détecteur lointain, SuperKamiokande. L'objectif de cette thèse est la mesure, avec le détecteur proche, de la composante intrinsèque de neutrinos électroniques dans le faisceau. Les TPC constituent le détecteur principal utilisé pour cette mesure. La première partie de la thèse décrit la méthode utilisée pour l'identification des particules (PID) : la méthode est basée sur la mesure de la moyenne tronquée de la charge déposée par les particules traversant le milieu gazeux. Les capacités de PID des TPC ont été testées avec des données en faisceau prises à TRIUMF avec un faisceau composé d'électrons, muons et pions ayant une impulsion jusqu'à 400 MeV. L'analyse de ces données confirme que la résolution sur l'énergie déposée dans la TPC est de l'ordre de 7%. Avec les premières données de l'expérience T2K une première mesure de la composante de neutrinos électroniques a été faite. Pour effectuer l'analyse, interactions de neutrinos dans ND280 ont été sélectionnées : cet échantillon est principalement composé par des interactions de neutrinos muoniques car les neutrinos électroniques sont de l'ordre de 1 % du nombre total de neutrinos dans le faisceau. La sélection avec le PID des neutrinos électroniques et muoniques, a permis une première mesure de la composante des neutrinos électroniques dans le faisceau de T2KThis thesis is devoted to the measurement of the electron neutrino appearance with the T2K experiment. T2K is a long baseline neutrino oscillation experiment that is taking data in Japan. The neutrino beam is produced by an accelerator in JPARC and neutrinos are observed in a Near Detector, ND280, before the oscillation and in the far detector, SuperKamiokande, after the oscillation. The aim of this thesis is the measurement of the intrinsic electron neutrino component of the beam with the Near Detector. The main detector used in this measurement is the ND280 TPC. The first part of the thesis describes the method developed for the particle identification in the TPCs: the PID method is based on the measurement of the truncated mean of the charge deposited by the particles crossing the gas. The PID capabilities of the TPCs have been tested analyzing the beam test data: these data have been taken at TRIUMF where we had a beam composed by electrons, muons and pions with momenta up to 400 MeV/c: the analysis of these data confirmed that the resolution on the deposited energy in the TPCs was of the order of 7%. When the first data of the T2K experiment were available, a first measurement of the electron neutrino component in the near detector has been done. To perform the analysis, a sample of neutrino interactions in ND280 was selected: this sample was mainly composed by muon neutrino interactions as the electron neutrino is expected to be 1 % of the total number of neutrinos in the beam. The selection of both, electron and muon neutrinos, allowed a first measurement of the electron neutrino component in the T2K beam
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Lin, Tzong-Yuan [Verfasser], Holger [Akademischer Betreuer] Dobbek, Wolfgang [Akademischer Betreuer] Lockau und Silke [Akademischer Betreuer] Leimkühler. „Electron transfer between the reductase and ferredoxin component of toluene dioxygenase / Tzong-Yuan Lin. Gutachter: Holger Dobbek ; Wolfgang Lockau ; Silke Leimkühler“. Berlin : Humboldt Universität zu Berlin, Mathematisch-Naturwissenschaftliche Fakultät I, 2012. http://d-nb.info/1026475228/34.
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Wommer, Michael [Verfasser], und J. [Akademischer Betreuer] Blümer. „Cross Calibration of the Measurements of the Electron Component of Extensive Air Showers of KASCADE-Grande and HEAT / Michael Wommer. Betreuer: J. Blümer“. Karlsruhe : KIT-Bibliothek, 2012. http://d-nb.info/1019790067/34.
Der volle Inhalt der QuelleBücher zum Thema "Electron-component"
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Kapustin, Vladimir, Aleksandr Sigov, Illarion Li und Vladimir Mel'nikov. Point defects in oxides and emission properties. ru: INFRA-M Academic Publishing LLC., 2022. http://dx.doi.org/10.12737/1846464.
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The monograph discusses the influence of point defects in oxides, which are the main emission component of cathodes of electrovacuum microwave devices, on their emission properties. The theory of electron emission of oxides, analytical methods for studying cathodes, methods for studying their emission properties are described. The issues of the theory and physicochemistry of nickel-oxide, metal-porous, metal-alloy and yttrium oxide cathodes, including cathodes for cold-start magnetrons, are considered in detail.
It is intended for scientific and engineering workers specializing in the field of electronic materials science and electronic devices. It can also serve as a textbook useful for teachers, graduate students, undergraduates, undergraduates of the corresponding physical-technical and natural-scientific specialties.
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Malins, Andrew Edward Russell. The development of a three component electron spin polarimeter. 2000.
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Horing, Norman J. Morgenstern. Interacting Electron–Hole–Phonon System. Oxford University Press, 2018. http://dx.doi.org/10.1093/oso/9780198791942.003.0011.
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Chapter 11 employs variational differential techniques and the Schwinger Action Principle to derive coupled-field Green’s function equations for a multi-component system, modeled as an interacting electron-hole-phonon system. The coupled Fermion Green’s function equations involve five interactions (electron-electron, hole-hole, electron-hole, electron-phonon, and hole-phonon). Starting with quantum Hamilton equations of motion for the various electron/hole creation/annihilation operators and their nonequilibrium average/expectation values, variational differentiation with respect to particle sources leads to a chain of coupled Green’s function equations involving differing species of Green’s functions. For example, the 1-electron Green’s function equation is coupled to the 2-electron Green’s function (as earlier), also to the 1-electron/1-hole Green’s function, and to the Green’s function for 1-electron propagation influenced by a nontrivial phonon field. Similar remarks apply to the 1-hole Green’s function equation, and all others. Higher order Green’s function equations are derived by further variational differentiation with respect to sources, yielding additional couplings. Chapter 11 also introduces the 1-phonon Green’s function, emphasizing the role of electron coupling in phonon propagation, leading to dynamic, nonlocal electron screening of the phonon spectrum and hybridization of the ion and electron plasmons, a Bohm-Staver phonon mode, and the Kohn anomaly. Furthermore, the single-electron Green’s function with only phonon coupling can be rewritten, as usual, coupled to the 2-electron Green’s function with an effective time-dependent electron-electron interaction potential mediated by the 1-phonon Green’s function, leading to the polaron as an electron propagating jointly with its induced lattice polarization. An alternative formulation of the coupled Green’s function equations for the electron-hole-phonon model is applied in the development of a generalized shielded potential approximation, analysing its inverse dielectric screening response function and associated hybridized collective modes. A brief discussion of the (theoretical) origin of the exciton-plasmon interaction follows.
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Lattman, Eaton E., Thomas D. Grant und Edward H. Snell. SAXS Instrumentation. Oxford University Press, 2018. http://dx.doi.org/10.1093/oso/9780199670871.003.0009.
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SAXS instrumentation is available for the laboratory, at the synchrotron, and at X-ray free electron laser sources. This chapter deals with SAXS instrumentation. It covers laboratory systems, synchrotron beamlines and newer sources. Multiple synchrotron facilities have SAXS beamlines and the ability to perform SAXS studies on free electron laser sources is growing. Sample handling has adopted automation and in some cases microfluidics to reduce sample volume requirements. Sensitive detectors efficient data collection software and rapid analysis allow real time decisions to be made during data collection. Specialized apparatus enables time resolved studies. Each component is described.
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Saitoh, E., und K. Ando. Experimental observation of the spin Hall effect using spin dynamics. Oxford University Press, 2017. http://dx.doi.org/10.1093/oso/9780198787075.003.0015.
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This chapter describes an experiment on the inverse spin Hall effect (ISHE) induced by spin pumping. Spin pumping is the generation of spin currents as a result of magnetization M(t) precession; in a ferromagnetic/paramagnetic bilayer system, a conduction-electron spin current is pumped out of the ferromagnetic layer into the paramagnetic conduction layer in a ferromagnetic resonance condition. The sample used in the experiment is a Ni81Fe19/Pt bilayer film comprising a 10-nm-thick ferromagnetic Ni81Fe19layer and a 10-nm-thick paramagnetic Pt layer. For the measurement, the sample system is placed near the centre of a TE011 microwave cavity at which the magnetic-field component of the microwave mode is maximized while the electric-field component is minimized.
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Dyall, Kenneth G., und Knut Faegri. Introduction to Relativistic Quantum Chemistry. Oxford University Press, 2007. http://dx.doi.org/10.1093/oso/9780195140866.001.0001.
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This book provides an introduction to the essentials of relativistic effects in quantum chemistry, and a reference work that collects all the major developments in this field. It is designed for the graduate student and the computational chemist with a good background in nonrelativistic theory. In addition to explaining the necessary theory in detail, at a level that the non-expert and the student should readily be able to follow, the book discusses the implementation of the theory and practicalities of its use in calculations. After a brief introduction to classical relativity and electromagnetism, the Dirac equation is presented, and its symmetry, atomic solutions, and interpretation are explored. Four-component molecular methods are then developed: self-consistent field theory and the use of basis sets, double-group and time-reversal symmetry, correlation methods, molecular properties, and an overview of relativistic density functional theory. The emphases in this section are on the basics of relativistic theory and how relativistic theory differs from nonrelativistic theory. Approximate methods are treated next, starting with spin separation in the Dirac equation, and proceeding to the Foldy-Wouthuysen, Douglas-Kroll, and related transformations, Breit-Pauli and direct perturbation theory, regular approximations, matrix approximations, and pseudopotential and model potential methods. For each of these approximations, one-electron operators and many-electron methods are developed, spin-free and spin-orbit operators are presented, and the calculation of electric and magnetic properties is discussed. The treatment of spin-orbit effects with correlation rounds off the presentation of approximate methods. The book concludes with a discussion of the qualitative changes in the picture of structure and bonding that arise from the inclusion of relativity.
Buchteile zum Thema "Electron-component"
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Soldatov, A. N. „MVL Parameter Management Through Electron Plasma Component“. In Pulsed Metal Vapour Lasers, 175–82. Dordrecht: Springer Netherlands, 1996. http://dx.doi.org/10.1007/978-94-009-1669-2_17.
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Zwickl, R. D., D. N. Baker, S. J. Barne, W. C. Feldman, S. A. Fuselier, W. F. Huebner, D. J. Mccomas und D. T. Young. „Three Component Plasma Electron Distribution in the Intermediate Ionized Coma of Comet Giacobini-Zinner“. In Special Publications, 401–4. Washington, D.C.: American Geophysical Union, 2013. http://dx.doi.org/10.1029/sp027p0181.
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Joshi, C., A. Caldwell, P. Muggli, S. D. Holmes und V. D. Shiltsev. „Outlook for the Future“. In Particle Physics Reference Library, 797–825. Cham: Springer International Publishing, 2020. http://dx.doi.org/10.1007/978-3-030-34245-6_12.
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AbstractThe charge separation between electrons and ions that exists within an electron plasma density wave can create large electric fields. In 1979 Tajima and Dawson first recognized that the longitudinal component of the field of a so-called “relativistic” wave (one propagating with a phase velocity close to c), could be used to accelerate charged particles to high energies in a short distance [1]. The accelerating gradient of such a plasma wave, Eo, can be approximated—assuming a total separation of electrons and ions in such a wave with wavelength λp = 2πc/ωp—as
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Takabe, Hideaki. „Non-local Transport of Electrons in Plasmas“. In Springer Series in Plasma Science and Technology, 285–323. Cham: Springer International Publishing, 2024. http://dx.doi.org/10.1007/978-3-031-45473-8_6.
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AbstractSince plasma is high temperature and the charge particles are running with high temperature, for example, at 1 keV, about the velocity of 109 (electron) and 2 × 107 (ion) [cm/s]. Since Coulomb mean-free-path is proportional to (velocity)4, higher velocity component transfers its energy over a long distance without Coulomb collision. This is usually called as “non-local transport” and the traditional diffusion model in neutral gas cannot be applicable. In laser plasma, the locally heated electron thermal energy is transported into cold over-dense region non-locally. The best way to solve such problem is to solve Fokker-Planck equation, while it is time consuming and some theoretical models have been proposed and studied over the last four decades. The physics of such models are explained here and most recent model SNB is shown and compared to experiments. The difficulty of transport of charges particles such as electrons is how to include the effect of electrostatic field and magnetic field self-consistently.
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Isihara, Akira. „One-Component Plasmas at High Temperatures“. In Electron Liquids, 41–54. Berlin, Heidelberg: Springer Berlin Heidelberg, 1998. http://dx.doi.org/10.1007/978-3-642-80392-5_3.
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Isihara, Akira. „One-Component Plasmas at High Temperatures“. In Electron Liquids, 43–56. Berlin, Heidelberg: Springer Berlin Heidelberg, 1993. http://dx.doi.org/10.1007/978-3-642-97303-1_3.
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Hornshøj, P., und M. Pfützner. „Study of the 1S Component of the Internal Bremsstrahlung Accompanying the (1u)-Forbidden Electron-Capture Decay of 41Ca“. In Weak and Electromagnetic Interactions in Nuclei, 49–51. Berlin, Heidelberg: Springer Berlin Heidelberg, 1986. http://dx.doi.org/10.1007/978-3-642-71689-8_10.
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Ogawa, Teruo. „Nad(P)H Dehydrogenase: A Component of PS-I Cyclic Electron flow Driving Inorganic Carbon Transport in Cyanobacteria“. In Research in Photosynthesis, 763–70. Dordrecht: Springer Netherlands, 1992. http://dx.doi.org/10.1007/978-94-009-0383-8_162.
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Gregor, Malcolm H. Mac. „Spatial Quantization and the Two-Component Rotation Group“. In The Enigmatic Electron, 99–106. Dordrecht: Springer Netherlands, 1992. http://dx.doi.org/10.1007/978-94-015-8072-4_13.
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Nuzillard, Danielle, und Noël Bonnet. „BSS for Series of Electron Energy Loss Spectra“. In Independent Component Analysis and Blind Signal Separation, 1150–57. Berlin, Heidelberg: Springer Berlin Heidelberg, 2004. http://dx.doi.org/10.1007/978-3-540-30110-3_145.
Der volle Inhalt der QuelleKonferenzberichte zum Thema "Electron-component"
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Litvinenko, Vladimir N., John M. J. Madey und Nikolai A. Vinokurov. „Component technologies for a recirculating linac free-electron laser“. In OE/LASE '94, herausgegeben von Jack V. Walker und Edward E. Montgomery IV. SPIE, 1994. http://dx.doi.org/10.1117/12.174187.
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Moiseenko, V. E., A. A. Ivanov, A. V. Anikeev und P. A. Bagryansky. „Antenna for electron component heating in the gas-dynamic trap“. In The twelfth topical conference on radio frequency power in plasmas. AIP, 1997. http://dx.doi.org/10.1063/1.53370.
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Wang, Jian, und Wendong Huang. „Research on TWT Frame Electron Gun Core Component Fabrication Technology“. In 2020 Cross Strait Radio Science & Wireless Technology Conference (CSRSWTC). IEEE, 2020. http://dx.doi.org/10.1109/csrswtc50769.2020.9372570.
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Vassali, M. R. „Principal component analysis for neural electron/jet discrimination in highly segmented calorimeters“. In ADVANCED COMPUTING AND ANALYSIS TECHNIQUES IN PHYSICS RESEARCH: VII International Workshop; ACAT 2000. AIP, 2001. http://dx.doi.org/10.1063/1.1405270.
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Longman, Fodio. „Comparative Analysis of Component Analysis Techniques for Secondary Electron Hyperspectral Imaging (SEHI)“. In European Microscopy Congress 2020. Royal Microscopical Society, 2021. http://dx.doi.org/10.22443/rms.emc2020.1062.
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Scherillo, F., S. Franchitti, R. Borrelli, C. Pirozzi, A. Squillace, A. Langella und L. Carrino. „Microstructural and micromechanical study of a Ti6Al4V component made by electron beam melting“. In ESAFORM 2016: Proceedings of the 19th International ESAFORM Conference on Material Forming. Author(s), 2016. http://dx.doi.org/10.1063/1.4963615.
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Novembre, Anthony E., Woon W. Tai, Janet M. Kometani, James E. Hanson, Omkaram Nalamasu, Gary N. Taylor, Elsa Reichmanis und Larry F. Thompson. „Single-component chemically amplified resist materials for electron-beam and x-ray lithography“. In Advances in Resist Technology and Processing VIII, herausgegeben von Hiroshi Ito. SPIE, 1991. http://dx.doi.org/10.1117/12.46361.
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Zinth, W., S. Schmidt, T. Arlt, H. Huber, T. Nägele, M. Meyer und H. Scheer. „Direct Observation of the Accessory Bacteriochlorophyll in the Primary Electron Transfer in Bacterial Reaction Centers“. In International Conference on Ultrafast Phenomena. Washington, D.C.: Optica Publishing Group, 1994. http://dx.doi.org/10.1364/up.1994.tub.7.
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Early femtosecond experiments on bacterial reaction centers (RC) performed nearly one decade ago did not exhibit transient absorption features related to the reduction of the accessory bacteriochlorophyll (B) located between the primary electron donor (the special pair P) and the electron accepting bacteriopheophytin H. The absence of such a component led to the conclusion that B is not a real electron carrying intermediate. However in later experiments |1–3| we found a subpicosecond component which had relatively weak amplitudes. The spectral dependence of this component and additional experiments on mutated and modified RC suggested that B is a real electron carrier. This interpretation was not generally accepted in the literature. One main objection came from the fact that the subpicosecond kinetic component was only observed in "congested" spectral region where other intermediates caused strong absorption changes. It is the purpose of this contribution to present new experimental results proving unambiguously that the accessory bacteriochlorophyll is a real electron carrier.
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Spears, Kenneth G., und Xiaoning Wen. „Vibrational Dynamics in Electron Transfer“. In Modern Spectroscopy of Solids, Liquids, and Gases. Washington, D.C.: Optica Publishing Group, 1995. http://dx.doi.org/10.1364/msslg.1995.stha2.
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Electron transfer is a widely studied and important phenomena with an extensive literature. The measurement of electron transfer (ET) rates as a function of vibrational state has been a long sought goal for testing the vibrational reorganization component of electron transfer. Prior insight into vibrational effects has been indirect, initially through correlations of rate versus exothermicity for a variety of compounds, and more recently through Raman spectroscopic identification of important vibrational modes. A direct electron transfer rate measurement for two vibrational states and subsequent identification of the final vibrational quantum numbers following electron transfer have been measured in our recent work for the first time.1
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Sgalaberna, Davide. „Measurement of the electron neutrino component of the T2K beam in the ND280 Tracker“. In The European Physical Society Conference on High Energy Physics. Trieste, Italy: Sissa Medialab, 2014. http://dx.doi.org/10.22323/1.180.0010.
Der volle Inhalt der QuelleBerichte der Organisationen zum Thema "Electron-component"
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Tang, J. Theory for electron-transfer reactions in a three-component system: The ``degenerate`` regime. Office of Scientific and Technical Information (OSTI), Februar 1994. http://dx.doi.org/10.2172/10118429.
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Dryepondt, Sebastien N., Bruce A. Pint und Daniel Ryan. Comparison of electron beam and laser beam powder bed fusion additive manufacturing process for high temperature turbine component materials. Office of Scientific and Technical Information (OSTI), April 2016. http://dx.doi.org/10.2172/1248786.
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Slattery, Kevin. Unsettled Topics on Surface Finishing of Metallic Powder Bed Fusion Parts in the Mobility Industry. SAE International, Januar 2021. http://dx.doi.org/10.4271/epr2021001.
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Laser and electron-beam powder bed fusion (PBF) additive manufacturing (AM) technology has transitioned from prototypes and tooling to production components in demanding fields such as medicine and aerospace. Some of these components have geometries that can only be made using AM. Initial applications either take advantage of the relatively high surface roughness of metal PBF parts, or they are in fatigue, corrosion, or flow environments where surface roughness does not impose performance penalties. To move to the next levels of performance, the surfaces of laser and electron-beam PBF components will need to be smoother than the current as-printed surfaces. This will also have to be achieve on increasingly more complex geometries without significantly increasing the cost of the final component. Unsettled Topics on Surface Finishing of Metallic Powder Bed Fusion Parts in the Mobility Industry addresses the challenges and opportunities of this technology, and what remains to be agreed upon by the industry.
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Dryepondt, Sebastien, Michael Kirka und Daniel Ryan. Comparison of Electron Beam and Laser Beam Powder Bed Fusion Additive Manufacturing Process for High Temperature Turbine Component Materials, Phase II. Office of Scientific and Technical Information (OSTI), Juni 2019. http://dx.doi.org/10.2172/1658007.
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Elbaum, Michael, und Peter J. Christie. Type IV Secretion System of Agrobacterium tumefaciens: Components and Structures. United States Department of Agriculture, März 2013. http://dx.doi.org/10.32747/2013.7699848.bard.
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Objectives: The overall goal of the project was to build an ultrastructural model of the Agrobacterium tumefaciens type IV secretion system (T4SS) based on electron microscopy, genetics, and immunolocalization of its components. There were four original aims: Aim 1: Define the contributions of contact-dependent and -independent plant signals to formation of novel morphological changes at the A. tumefaciens polar membrane. Aim 2: Genetic basis for morphological changes at the A. tumefaciens polar membrane. Aim 3: Immuno-localization of VirB proteins Aim 4: Structural definition of the substrate translocation route. There were no major revisions to the aims, and the work focused on the above questions. Background: Agrobacterium presents a unique example of inter-kingdom gene transfer. The process involves cell to cell transfer of both protein and DNA substrates via a contact-dependent mechanism akin to bacterial conjugation. Transfer is mediated by a T4SS. Intensive study of the Agrobacterium T4SS has made it an archetypal model for the genetics and biochemistry. The channel is assembled from eleven protein components encoded on the B operon in the virulence region of the tumor-inducing plasmid, plus an additional coupling protein, VirD4. During the course of our project two structural studies were published presenting X-ray crystallography and three-dimensional reconstruction from electron microscopy of a core complex of the channel assembled in vitro from homologous proteins of E. coli, representing VirB7, VirB9, and VirB10. Another study was published claiming that the secretion channels in Agrobacterium appear on helical arrays around the membrane perimeter and along the entire length of the bacterium. Helical arrangements in bacterial membranes have since fallen from favor however, and that finding was partially retracted in a second publication. Overall, the localization of the T4SS within the bacterial membranes remains enigmatic in the literature, and we believe that our results from this project make a significant advance. Summary of achievements : We found that polar inflations and other membrane disturbances relate to the activation conditions rather than to virulence protein expression. Activation requires low pH and nutrient-poor medium. These stress conditions are also reflected in DNA condensation to varying degrees. Nonetheless, they must be considered in modeling the T4SS as they represent the relevant conditions for its expression and activity. We identified the T4SS core component VirB7 at native expression levels using state of the art super-resolution light microscopy. This marker of the secretion system was found almost exclusively at the cell poles, and typically one pole. Immuno-electron microscopy identified the protein at the inner membrane, rather than at bridges across the inner and outer membranes. This suggests a rare or transient assembly of the secretion-competent channel, or alternatively a two-step secretion involving an intermediate step in the periplasmic space. We followed the expression of the major secreted effector, VirE2. This is a single-stranded DNA binding protein that forms a capsid around the transferred oligonucleotide, adapting the bacterial conjugation to the eukaryotic host. We found that over-expressed VirE2 forms filamentous complexes in the bacterial cytoplasm that could be observed both by conventional fluorescence microscopy and by correlative electron cryo-tomography. Using a non-retentive mutant we observed secretion of VirE2 from bacterial poles. We labeled the secreted substrates in vivo in order detect their secretion and appearance in the plant cells. However the low transfer efficiency and significant background signal have so far hampered this approach.
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Gafny, Ron, A. L. N. Rao und Edna Tanne. Etiology of the Rugose Wood Disease of Grapevine and Molecular Study of the Associated Trichoviruses. United States Department of Agriculture, September 2000. http://dx.doi.org/10.32747/2000.7575269.bard.
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Rugose wood is a complex disease of grapevines, characterized by modification of the woody cylinder of affected vines. The control of rugose wood is based on the production of healthy propagation material. Detection of rugose wood in grapevines is difficult and expensive: budwood from tested plants is grafted onto sensitive Vitis indicators and the appearance of symptoms is monitored for 3 years. The etiology of rugose wood is complex and has not yet been elucidated. Several elongated clostero-like viruses are consistently found in affected vines; one of them, grapevine virus A (GVA), is closely associated with Kober stem grooving, a component of the rugose wood complex. GVA has a single-stranded RNA genome of 7349 nucleotides, excluding a polyA tail at the 3' terminus. The GVA genome includes five open reading frames (ORFs 1-5). ORF 4, which encodes for the coat protein of GVA, is the only ORF for which the function was determined experimentally. The original objectives of this research were: 1- To produce antisera to the structural and non-structural proteins of GVA and GVB and to use these antibodies to establish an effective detection method. 2- Develop full length infectious cDNA clones of GVA and GVB. 3- Study the roll of GVA and GVB in the etiology of the grapevine rugose wood disease. 4- Determine the function of Trichovirus (now called Vitivirus) encoded genes in the virus life cycle. Each of the ORFs 2, 3, 4 and 5 genes of GVA were cloned and expressed in E. coli and used to produce antisera. Both the CP (ORF 4) and the putative MP (ORF 3) were detected with their corresponding antisera in-GVA infected N. benthamiana and grapevine. The MP was first detected at an early stage of the infection, 6-12 h after inoculation, and the CP 2-3 days after inoculation. The MP could be detected in GVA-infected grapevines that tested negative for CP, both with CP antiserum and with a commercially available ELISA kit. Antisera to ORF 2 and 5 encoded proteins could react with the recombinant proteins but failed to detect both proteins in GVA infected plants. A full-length cDNA clone of grapevine virus A (GVA) was constructed downstream from the bacteriophage T7 RNA polymerase promoter. Capped in vitro transcribed RNA was infectious in N. benthamiana and N. clevelandii plants. Symptoms induced by the RNA transcripts or by the parental virus were indistinguishable. The infectivity of the in vitro-transcribed RNA was confirmed by serological detection of the virus coat and movement proteins and by observation of virions by electron microscopy. The full-length clone was modified to include a gus reporter gene and gus activity was detected in inoculated and systemic leaves of infected plants. Studies of GVA mutants suggests that the coat protein (ORF 4) is essential for cell to cell movement, the putative movement protein (ORF 3) indeed functions as a movement protein and that ORF 2 is not required for virus replication, cell to cell or systemic movement. Attempts to infect grapevines by in-vitro transcripts, by inoculation of cDNA construct in which the virus is derived by the CaMV 35S promoter or by approach grafting with infected N. benthamiana, have so far failed. Studies of the subcellular distribution of GFP fusion with each of ORF 2, 3 and 4 encoded protein showed that the CP fusion protein accumulated as a soluble cytoplasmatic protein. The ORF 2 fusion protein accumulated in cytoplasmatic aggregates. The MP-GFP fusion protein accumulated in a large number of small aggregates in the cytoplasm and could not move from cell to cell. However, in conditions that allowed movement of the fusion protein from cell to cell (expression by a PVX vector or in young immature leaves) the protein did not form cytoplasmatic aggregates but accumulated in the plasmodesmata.
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Splitter, Gary A., Menachem Banai und Jerome S. Harms. Brucella second messenger coordinates stages of infection. United States Department of Agriculture, Januar 2011. http://dx.doi.org/10.32747/2011.7699864.bard.
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Aim 1: To determine levels of this second messenger in: a) B. melitensiscyclic-dimericguanosinemonophosphate-regulating mutants (BMEI1448, BMEI1453, and BMEI1520), and b) B. melitensis16M (wild type) and mutant infections of macrophages and immune competent mice. (US lab primary) Aim 2: To determine proteomic differences between Brucelladeletion mutants BMEI1453 (high cyclic-dimericguanosinemonophosphate, chronic persistent state) and BMEI1520 (low cyclicdimericguanosinemonophosphate, acute virulent state) compared to wild type B. melitensisto identify the role of this second messenger in establishing the two polar states of brucellosis. (US lab primary with synergistic assistance from the Israel lab Aim 3: Determine the level of Brucellacyclic-dimericguanosinemonophosphate and transcriptional expression from naturally infected placenta. (Israel lab primary with synergistic assistance from the US lab). B. Background Brucellaspecies are Gram-negative, facultative intracellular bacterial pathogens that cause brucellosis, the most prevalent zoonosis worldwide. Brucellosis is characterized by increased abortion, weak offspring, and decreased milk production in animals. Humans are infected with Brucellaby consuming contaminated milk products or via inhalation of aerosolized bacteria from occupational hazards. Chronic human infections can result in complications such as liver damage, orchitis, endocarditis, and arthritis. Brucellaspp. have the ability to infect both professional and non-professional phagocytes. Because of this, Brucellaencounter varied environments both throughout the body and within a cell and must adapt accordingly. To date, few virulence factors have been identified in B. melitensisand even less is known about how these virulence factors are regulated. Subsequently, little is known about how Brucellaadapt to its rapidly changing environments, and how it alternates between acute and chronic virulence. Our studies suggest that decreased concentrations of cyclic dimericguanosinemonophosphate (c-di-GMP) lead to an acute virulent state and increased concentrations of c-di-GMP lead to persistent, chronic state of B. melitensisin a mouse model of infection. We hypothesize that B. melitensisuses c-di-GMP to transition from the chronic state of an infected host to the acute, virulent stage of infection in the placenta where the bacteria prepare to infect a new host. Studies on environmental pathogens such as Vibrio choleraeand Pseudomonas aeruginosasupport a mechanism where changes in c-di-GMP levels cause the bacterium to alternate between virulent and chronic states. Little work exists on understanding the role of c-di-GMP in dangerous intracellular pathogens, like Brucellathat is a frequent pathogen in Israeli domestic animals and U.S. elk and bison. Brucellamust carefully regulate virulence factors during infection of a host to ensure proper expression at appropriate times in response to host cues. Recently, the novel secondary signaling molecule c-di-GMP has been identified as a major component of bacterial regulation and we have identified c-di-GMP as an important signaling factor in B. melitensishost adaptation. C. Major conclusions, solutions, achievements 1. The B. melitensis1453 deletion mutant has increased c-di-GMP, while the 1520 deletion mutant has decreased c-di-GMP. 2. Both mutants grow similarly in in vitro cultures; however, the 1453 mutant has a microcolony phenotype both in vitro and in vivo 3. The 1453 mutant has increased crystal violet staining suggesting biofilm formation. 4. Scanning electron microscopy revealed an abnormal coccus appearance with in increased cell area. 5. Proteomic analysis revealed the 1453 mutant possessed increased production of proteins involved in cell wall processes, cell division, and the Type IV secretion system, and a decrease in proteins involved in amino acid transport/metabolism, carbohydrate metabolism, fatty acid production, and iron acquisition suggesting less preparedness for intracellular survival. 6. RNAseq analysis of bone marrow derived macrophages infected with the mutants revealed the host immune response is greatly reduced with the 1453 mutant infection. These findings support that microlocalization of proteins involved in c-di-GMP homeostasis serve a second messenger to B. melitensisregulating functions of the bacteria during infection of the host.