Дисертації з теми "Decay stage"

Loss of dead wood habitat and biodiversity has led to numerous excellent conservation based ecological and management studies. However, the structure of the xylophagous food web remains unclear for saproxylic xylophagous beetles and their parasitoid wasps, but fungi are believed to play an important role, both in direct and indirect nutritional acquisition and production of volatile chemicals. In the first study of its kind this thesis explores the importance of volatiles in host-searching behaviour and role of fungi in oviposition choice and larval nutrition, using three endophytic fungi, Stereum hirsutum, Stereum gausapatum and Eutypa spinosa, and two tree species Fagus sylvatica and Quercus robur, in early stage decay. Newly designed traps, excluding wood visual stimuli, provided the first evidence of wood-fungal volatile attraction by saproxylic wood-boring beetles, including primary and secondary xylophages, and their parasitoid wasps. Expanding on these results, the importance of fungi was further demonstrated through oviposition choice in field logs by two polyphagous cerambycid species. Ovipositing within or 20 mm from their preferred fungal species plug, females chose abiotic conditions suitable for sustaining fungal growth, suggesting a larval nutritional benefit. Further investigation, using one of the cerambycid species above, corroborated, via olfactometry, that volatiles from the preferred wood-fungal combination were attractants to gravid females, and induced ovipositor probing within the olfactometer. In addition, GC-EAG found six volatile compounds provoked an antennal response, including a monoterpene, two sesquiterpenes, an alkane and a ketone. Most importantly olfactometry and GC-EAG showed gravid females were unresponsive to wood or favored fungus presented singly. The result are discussed herein. In conjunction with the volatile only field trap experiment, a novel method to promote fungal only volatiles, by autoclaving the wood prior to sub-culturing, was trialed. GC-MS comparative analysis showed disparity between agar sub-cultured, autoclaved wood and natural wood with fungi, volatiles. This suggests that genes encoding cellulases and hemicellulases are regulated according to carbohydrate source, nutritional availability, oxygen and metal ions, supporting the variations observed. These results are discussed herein with regard to xylophagous beetles and their parasitoid wasps. The principal findings of this thesis are that wood-fungal interaction volatiles of the ephemeral early decay stage provide important olfactory host resource cues for saproxylic xylophagous beetles and their parasitoid wasps. Fungi, and particular, endophytic fungi, were shown to be a key component of the early stage xylophagous food web through volatile production, and as nutritional support evidenced by oviposition choice, olfactometry, GC-EAG and GC-MS analysis. This thesis has opened a new, exciting and important area of research with the potential to radically improve conservation management and employ a more holistic approach. These insights bring together the disparate research conducted individually on wood decay fungi, saproxylic xylophagous beetles and their parasitoid wasps

The introduction of general numerical methods in the form of widely available software can have a dramatic effect on the development of a scientific field. In electronic structure theory, for example, general-purpose programs (such as Gaussian, ADF, MOLPRO,. . . ) combined with better computational resources have in part led to molecular electronic structure calculations becoming a ubiquitous tool in chemical research. Similarly, quantum dynamics methods based on coupled time-evolving Gaussian basis sets and molecular potential energy surfaces calculated on-the-fly hold out similar promise in the study of non-adiabatic processes, because of their generality and freedom from ad hoc assumptions. Therefore, the aim of this thesis is to investigate the convergence and applicability of quantum dynamics calculations with a fully variational coupled Gaussian basis set description, termed variational Multi-Con guration Gaussian (vMCG). It is suggested that the vMCG approach provides a way to balance accuracy against computational cost for molecules of comparable size by choosing the number of coupled Gaussian product basis functions and a middle way forward between grid-based and trajectory surface hopping approaches to non-adiabatic molecular quantum dynamics calculations. In order to prove the suitability of vMCG we show its application to three problems of chemical interest: the study of fulvene excited state decay, the prediction of a coherent control mechanism for the same system and the benchmarking of an electronic population dynamics model for electronic transitions when occurring through a conical intersection. In the long term, the development of vMCG is expected to have a major impact, allowing nonadiabatic dynamics simulations to be made not only by theoreticians, but also by non-specialists and experimentalists in both industry and academia.Chapter 1: Modelling Excited State Decay [Diagrams appear here. To view, please open pdf attachment] This chapter introduces and reviews the current state-of-the-art modelling of non-adiabatic processes in molecular systems. This is a challenging topic since the simulation must treat simultaneously the motion of the nuclei and the electrons, which are coupled together. It is concluded that a wide range of methodologies are available. However, when looking for a general tool for the study of non-adiabatic processes, quantum dynamics methods based on coupled time-evolving Gaussian basis sets such as the Direct Dynamics variational Multi-Con guration Gaussian (DD-vMCG) wavepacket method, as well as to other related methods - such as Ab Initio Multiple Spawning (AIMS, FMS)[1, 2] and Multi-Con gurational Ehrenfest (MCE)[3, 4] - seem to be an especially suitable choice because of their generality and freedom from ad hoc assumptions. Chapter 2: variational Gaussian nuclear wavepackets [Diagrams appear here. To view, please open pdf attachment] This chapter describes three possible time-evolving Gaussian basis sets for use in non-adiabatic quantum dynamics based on the Direct Dynamics variational Multi-Con guration Gaussian (DD-vMCG) wavepacket method. These general model representations are compared using model calculations in a simple harmonic oscillator and describing their connections to other work. It is suggested that the fully variational nuclear wavefunction, termed vMCG (variational Multi-Con guration Gaussian) is a very convenient formulation leading towards a realistic sampling of the phase space without the initial conditions (i.e. initial disposition and momentum) being so important when using a su cient amount of coupled Gaussian basis functions. Chapter 3: Fulvene S1/S0 Excited State Decay [Diagrams appear here. To view, please open pdf attachment] The vMCG (variational Multi-Con guration Gaussian) approach described in Chapter 2 is benchmarked in a realistic system by modelling the radiationless decay from an electronic excited state through an extended conical intersection seam. As a benchmark system, we model the radiationless decay of fulvene from its rst electronic excited state and monitor two associated properties: the spatial extent to which the conical intersection seam is sampled and the timescale and stepwise nature of the population transfer. We illustrate how the use of a fully variational nuclear wavefunction provides a way to balance accuracy against computational cost for molecules of comparable size by choosing the number of coupled Gaussian product basis functions. Chapter 4: Controlling Fulvene S1/S0 Decay [Diagrams appear here. To view, please open pdf attachment] Direct quantum dynamics simulations using the vMCG (variational Multi- Con guration Gaussian) approach were performed in order to model the control of the stepwise population transfer in fulvene. As shown in Chapter 3, ultra-fast internal conversion takes place centred on the higher-energy planar/sloped region of the S1/S0 conical intersection seam. Therefore, two possible schemes for controlling whether stepwise population transfer occurs or not | either altering the initial geometry distribution or the initial momentum composition of the photo-excited wavepacket - were explored. In both cases, decay took place instead in the lower-energy twisted/peaked region of the crossing seam, switching o the stepwise population transfer. This absence of re-crossing is a direct consequence of the change in the position on the intersection at which decay occurs and its consequences should provide an experimentally observable fingerprint of this system. Chapter 5: A population transfer model for intramolecular electron transfer [Diagrams appear here. To view, please open pdf attachment] The aim of this chapter is to further prove the applicability of the vMCG (variational Multi-Con guration Gaussian) approach by benchmarking an approximate population dynamics model in Jahn-Teller systems. The socalled Density Matrix Non-Equilibrium Fermi Golden Rule (DM-NFGR) can be seen as a simpli ed version of vMCG, in which the nite Gaussian basis set and on-the-fly evaluation of the nuclear Hamiltonian are eliminated via use of the density matrix formalism and a perturbational treatment of the equations. This has three clear advantages: firstly, it allows us to extend the maximum molecular size considerably; secondly, we can relate the population dynamics to an analytical time-dependent rate expression; and finally, temperature effects can be included in the simulations. Benchmark calculations for the 2,6-bis(methylene) adamantyl (BMA) radical cation support the reliability of the results.

The question of a possible finite neutrino mass is one of the most investigated and controversial topics in particle physics and cosmology. The most promising direct ex periments for determining the neutrino mass are based on the study of the /-decay of molecular tritium. The mass of the neutrino is deduced by analysing the shape of the continuous energy spectrum of the electrons emitted in the /3-decay. In this thesis, the molecular physics issues facing these experiments are investigated. Theoretical final state probability distributions of the daughter molecule are calculated to satisfy the higher resolution requirements and increased sensitivity of the future ex periments. Transition probabilities to the six lowest electronically bound states of 3HeT+ are calculated. Rotational excitation of the daughter molecule is considered and probabilities obtained for the /-decay of T2 in the first four rotational states. Isotope contamination from DT and HT molecules is also investigated, and the probability distributions for 3HeD+ and 3HeH+ are calculated. The sensitivity of the initial temperature, ortho:para ratio and isotopic composition of the source is considered. Estimates of the error in the value of the neutrino mass deduced from fitting theoretical spectra, due to uncertainties in temperature, ortho:para ratio of T2 and percentage of DT molecules, are obtained. The R-matrix method is used to treat the electronic continuum of 3HeT+. Reso nances converging to the first eight excited target states are obtained, and the transition probabilities to these resonances and background continuum are calculated. Endpoint effects due to the decay of other possible species in the source - T_, T, T+, T2", Tg and T - are also investigated. It is hoped that this data will be used as part of the forthcoming KATRIN experi ment.

Aquesta tesi doctoral se centra en l’estudi teòric i numèric de sistemes fotònics amb retroacció i múltiples línies de retard, en el límit en el que els temps de retard són molt més grans que les escales de temps intrínseques del sistema. Es consideren dos sistemes òptics amb retroacció: i) dos oscilıladors optoelèctronics (OEOs) acoblats mútuament amb retard i ii) un làser de semiconductor amb retard que depèn de l’estat mitjançant el filtrat freqüencial des de dues cavitats amb diferents longituds i freqüències centrals. Tot i que els dos sistemes tenen en comú la presència de múltiples línies de retard, es tracta de dos sistemes ben diferents. En el primer, intevenen en tot moment dos temps de retard. En el segon, en canvi, la llum pren una única línia de retard a cada moment; en aquest sistema, el valor del retard és seleccionat intrínsicament per l’estat del sistema d’entre dos valors diferents mitjançant el filtrat freqüencial de la llum des de dos filtres de diferents freqüències centrals colılocats en dues cavitats de diferent longitud. D’una banda, es modelitzen aquests sistemes i es desenvolupen mètodes analítics per trobar solucions aproximades. Aquests mètodes es podrien emprar per entendre la dinàmica d’altres sistemes amb retard. D’altra banda, es comparen els resultats analítics o experimentals amb simulacions numèriques. La tesi està dividida en quatre parts. Les parts I, II i IV contenen diversos capítols, mentre que la part III està formada per un únic capítol. La part I, Introducció, objectius, eines i resultats anteriors , està dividida en tres capítols: En el Capítol 1, primer s’introdueixen alguns exemples de sistemes en els quals la presència de retards determina les propietats dinàmiques del sistema i en alguns casos origina un comportament complex. A continuació, s’introdueix el problema genèric d’un sistema amb retard i la seva modelització mitjançant equacions diferencials amb retard. S’expliquen dos exemples en detall, incloent la seva modelització amb equacions diferencials amb retard. Més endavant, s’introdueixen les ones quadrades que es poden obtenir amb sistemes d’OEOs i altres sistemes amb retard, i es presenten algunes aplicacions de les solucions tipus ona quadrada obtingudes amb OEOs, com són el control del període o la codificació d’informació. Finalment es resumeixen els objectius de la tesi. En el Capítol 2, es presenten alguns mètodes analítics i numèrics emprats en aquesta tesi, com són el mètode d’estabilitat lineal, l’estudi de l’estabilitat de solucions periòdiques, i algoritmes per integrar numèricament equacions diferencials amb retard. El Capítol 3 està dedicat a l’estudi de la dinàmica de sistemes senzills en els quals els sistemes d’estudi d’aquesta tesi estan basats: un oscilılador optoelectrònic i un làser de semiconductor amb retroacció òptica. En cada cas, es descriu el sistema en detall, s’introdueix la seva modelització mitjançant equacions diferencials amb retard, i es presenten els diferents tipus de dinàmica i possibles aplicacions. La part II està dedicada a la Sincronització en oscil·ladors optoelectrònics mú- tuament acoblats amb retard i conté quatre capítols: En el Capítol 4, es descriu el sistema de dos OEOs mútuament acoblats i amb dos temps de retard diferents, el de la retroacció i el de l’acoblament. Primer s’obtenen les equacions dinàmiques del sistema. A continuació, s’escriuen les equacions dinàmiques de manera adimensional i es troba l’estat estacionari estàtic (punt fix) del sistema. Per acabar, s’introdueix el cas d’OEOs idèntics, se simplifiquen les equacions dinàmiques i es demostra l’existència de solucions periòdiques sincronitzades en fase i en antifase a partir de l’anàlisi d’estabilitat lineal de la solució zero. El Capítol 5 se centra en la generació de solucions periòdiques quadrades mitjançant el sistema de dos OEOs idèntics mútuament acoblats descrit en el capítol 4, en el cas de retroacció negativa, la qual tendeix a reduir l’efecte de les pertorbacions de l’estat estacionari estàtic. Primer s’aplica el mètode d’estabilitat lineal per trobar el període de les solucions oscilılants en funció de la relació entre els dos temps de retard diferents. Es demostra la coexistència de múltiples solucions periòdiques de tipus ona quadrada sincronitzades en fase quan la raó entre el temps de retard intrínsec i el de l’acoblament satisfà una relació racional entre dos nombres senars. De manera similar, múltiples ones quadrades en antifase i amb diferents períodes poden coexistir quan la raó entre el temps de retard intrínsec i el de l’acoblament és un racional senar/parell. A continuació, s’apliquen mètodes assimptòtics per obtenir mapes per a l’amplada de les solucions. Es demostra que les solucions periòdiques quadrades experimenten una ruta al caos del tipus doblament de període. Després s’analitza l’efecte de canviar lleugerament els paràmetres en la forma de les solucions. Finalment, a partir del càlcul precís del període de les solucions, s’observa un fenomen de divisió del període en diferents valors. El Capítol 6 està dedicat a l’aparició de solucions quadrades estables amb el mateix model que en el Capítol 5, però en el cas de retroacció positiva, la qual tendeix a augmentar l’efecte de les pertorbacions de l’estat estacionari estàtic. Les solucions quadrades que apareixen amb retroacció positiva tenen un cicle asimètric i són més flexibles i robustes que les que s’obtenen amb retroacció negativa; en concret, l’asimetria del seu cicle permet que puguin adaptar la seva forma com a resposta a canvis en els valors dels paràmetres. Primer s’aplica l’anàlisi d’estabilitat lineal de l’estat estacionari estàtic per obtenir el període de les ones quadrades de freqüència més gran en funció de la relació entre els dos temps de retard diferents. Es demostra que el sistema té solucions sincronitzades en fase i en antifase, i que múltiples solucions poden coexistir, de manera similar al cas de retroacció negativa. No obstant això, a diferència del cas de retroacció negativa, aquí les solucions en antifase sempre coexisteixen amb solucions en fase amb diferents períodes. A més, aquest sistema té solucions periòdiques de freqüència més baixa, sincronitzades en fase i que coexisteixen amb les ones quadrades de freqüència alta per als mateixos valors dels paràmetres. A continuació, s’aplica un mètode assimptòtic per caracteritzar l’amplitud i la forma de les ones quadrades. Es demostra que el cicle de les solucions quadrades generades amb retroacció positiva es pot controlar canviant el voltatge constant aplicat als OEOs, sense que canviï el període. També s’analitza l’efecte de canviar lleugerament els valors dels paràmetres en la forma de les solucions. Es demostra que les ones quadrades generades amb retroacció positiva són més robustes a canvis en els valors dels paràmetres. Finalment, a partir del càlcul precís del període de les solucions, s’observa un fenomen de divisió del període en diferents valors. En el Capítol 7, s’estudia el cas de dos oscilıladors no-idèntics, incloent les possibilitats de retroacció negativa, positiva i mixta. Es demostra que aquest sistema pot generar múltiples solucions de tipus ona quadrada, amb diferents tipus de sincronització (en fase, en antifase i a un quart del període) depenent del signe de la retroacció de cada oscilılador. Les ones quadrades amb sincronització a un quart del període apareixen principalment quan la retroacció és negativa per a un oscilılador i positiva per a l’altre. Finalment, s’analitza la robustesa de les solucions sincronitzades a un quart del període a petits canvis en els valors dels paràmetres. La part III se centra en el tema Sistemes fotònics amb retards que depenen de l'estat i està formada per un capítol: En el Capítol 8, es considera un sistema de làser de semiconductor amb filtrat freqüencial des de dues cavitats de longituds i freqüències centrals diferents, com a model per a estudiar la dinàmica d’un sistema amb retard que depèn de l’estat. Primer s’introdueix el disseny experimental, que està basat en un làser de semiconductor i dos filtres de Bragg amb diferents freqüències centrals colılocats en dues cavitats de diferents longituds, i per tant associats a dos temps de retard diferents. Es demostra que la dinàmica d’aquest sistema es caracteritza per salts erràtics entre els dos valors del temps de retard. A continuació, s’introdueix un model teòric amb filtrat lorentzià des de dues cavitats diferents. Es calculen les solucions estacionàries i s’analitza la dinàmica erràtica amb retard que depèn de l’estat per a diferents valors dels paràmetres. Es demostra que els resultats numèrics en el règim erràtic coincideixen qualitativament amb els experiments. També es demostra que aquest sistema té solucions més regulars, similars a les ones quadrades periòdiques, amb retard que depèn de l’estat. Finalment, s’analitza l’estadística dels temps de residència durant els quals el retard pren un valor constant. La part IV, Resum i perspectives de treball, conté dos capítols de conclusions: el Capítol 9, corresponent a la part dels OEOs; i el Capítol 10, referit a la part dels retards depenents de l’estat. En aquests capítols es resumeixen els principals resultats obtinguts i es proposen algunes perspectives per a futures investigacions.
Esta tesis doctoral se centra en el estudio teórico y numérico de sistemas fotónicos con realimentación y múltiples líneas de retardo, en el límite en el que los tiempos de retardo son mucho más grandes que las escalas de tiempo intrínsecas del sistema. Se consideran dos sistemas ópticos con realimentación: i) dos osciladores optoelectrónicos (OEOs) mutuamente acoplados con retardo y ii) un láser de semiconductor con retardo dependiente del estado mediante el filtrado frecuencial desde dos cavidades con diferentes longitudes y frecuencias centrales. Aunque estos dos sistemas tienen en común la presencia de múltiples líneas de retardo, se trata de dos sistemas bastante diferentes. En el primero en todo momento intervienen dos tiempos de retardo. En el segundo, en cambio, la luz toma una única línea de retardo en cada momento; en este sistema, el valor del retardo es seleccionado intrínsicamente por el estado del sistema entre dos valores diferentes mediante el filtrado frecuencial de la luz desde dos filtros con diferentes frecuencias centrales colocados en dos cavidades de diferente longitud. Por un lado, se modelizan estos sistemas y se desarrollan métodos analíticos para encontrar soluciones aproximadas. Estos métodos podrían utilizarse para comprender la dinámica de otros sistemas con retardo. Por otro lado, se contrastan los resultados analíticos o experimentales con simulaciones numéricas. La tesis está dividida en cuatro partes. Las partes I, II y IV contienen varios capítulos, mientras que la parte III está formada por un solo capítulo. La parte I, Introducción, objectivos, herramientas y resultados anteriores , está dividida en tres capítulos: En el Capítulo 1, primero se introducen algunos ejemplos de sistemas en los cuales la presencia de retardos determina las propiedades dinámicas del sistema, en algunos casos dando lugar a comportamiento complejo. A continuación se presenta el problema general de un sistema con retardo y su modelización con ecuaciones diferenciales con retardo. Se explican dos ejemplos en detalle, incluyendo su modelización con ecuaciones diferenciales con retardo. Luego se introduce el régimen dinámico de oscilación periódica de tipo onda cuadrada que se puede obtener con OEOs y otros sistemas con retardo, y se resaltan algunas aplicaciones de estas ondas cuadradas, como el control del período y la codificación de información. El capítulo termina con un resumen de los objetivos de la tesis. En el Capítulo 2, se introducen algunos métodos numéricos y teóricos usados en esta tesis, como el análisis de estabilidad lineal, métodos y herramientas para el estudio de la estabilidad de soluciones periódicas, y algoritmos para integrar numéricamente las ecuaciones diferenciales con retardo. El Capítulo 3 está dedicado al estudio de la dinámica de sistemas sencillos en los que se basan los sistemas estudiados en esta tesis: un único OEO y un láser de semiconductor con realimentación óptica. En cada caso, se describe en detalle el sistema, se introduce su modelización con ecuaciones diferenciales con retardo, y se presentan sus diferentes regímenes dinámicos y posibles aplicaciones. La parte II está dedicada a la Sincronización en osciladores optoelectrónicos mutuamente acoplados con retardo y contiene cuatro capítulos: En el Capítulo 4, se describe el sistema de dos OEOs mutuamente acoplados y con dos tiempos de retardo diferentes, el de la propia realimentación y el del acoplamiento. Primero se derivan las ecuaciones dinámicas del sistema. A continuación se escriben las ecuaciones dinámicas en forma adimensional y se calcula la solución estacionaria estática (punto fijo) del sistema. Finalmente se introduce el caso de OEOs idénticos, se simplifican las ecuaciones dinámicas y se demuestra que el análisis de estabilidad lineal de la solución cero da lugar a soluciones periódicas sincronizadas en fase y en antifase. El Capítulo 5 se centra en la generación de pulsos simétricos de onda cuadrada mediante el sistema de dos OEOs idénticos mutuamente acoplados con retardo descrito en el capítulo 4, en el caso de realimentacion negativa, la cual tiende a reducir el efecto de las perturbaciones del estado etacionario estático. Primero se aplica el método de estabilidad lineal para obtener el período de las soluciones oscilatorias en función de la relación entre los dos tiempos de retardo diferentes. Se demuestra que múltiples soluciones periódicas de tipo onda cuadrada en fase coexisten cuando la razón entre el tiempo de retardo intrínseco y el del acoplamiento satisface una relación racional entre dos números impares. De manera similar, múltiples ondas cuadradas en antifase con diferentes períodos pueden coexistir cuando la razón entre el tiempo de retardo intrínseco y el del acoplamiento es un racional impar/- par. A continuación, se aplican métodos asintóticos para obtener mapas para la amplitud de las soluciones. Se demuestra que las ondas cuadradas periódicas experimentan una ruta al caos del tipo doblamiento de período. Después se analiza el efecto de cambiar ligeramente los valores de los parámetros en la forma de las soluciones. Finalmente, a partir del cálculo preciso del período de las soluciones, se observa un fenómeno de división del período en diferentes valores. El Capítulo 6 está dedicado a la aparición de pulsos de onda cuadrada estables con el mismo modelo que en el Capítulo 5 pero en el caso de realimentación positiva, la cual tiende a aumentar el efecto de las perturbaciones del estado etacionario estático. Las ondas cuadradas que surgen con realimentación positiva tienen un ciclo asimétrico y son más flexibles y robustas que las obtenidas con realimentación negativa; en particular, la asimetría de su ciclo les permite adaptar su forma en respuesta a cambios en los valores de los parámetros en vez de experimentar un doblamiento de período. Primero se aplica el análisis de estabilidad lineal del estado estacionario estático para obtener el período de las ondas cuadradas de mayor frecuencia en función de la relación entre los dos tiempos de retardo diferentes. Se demuestra que el sistema tiene soluciones sincronizadas en fase y en antifase, y que múltiples soluciones pueden coexistir, de manera similar al caso de realimentación negativa. Sin embargo, a diferencia del caso de realimentación negativa, aquí las soluciones en antifase siempre coexisten con soluciones en fase con diferentes períodos. Además, este sistema tiene soluciones periódicas de menor frecuencia, sincronizadas en fase y coexistiendo con las soluciones cuadradas rápidas para los mismos valores de los parámetros. A continuación se aplica un método asintótico para determinar la amplitud y forma de las ondas cuadradas. Se demuestra que el ciclo de las ondas cuadradas generadas con realimentación positiva se puede controlar cambiando el voltaje constante aplicado a los OEOs, manteniendo el período constante. También se analiza el efecto de variar ligeramente los valores de los parámetros en la forma de las soluciones. Se demuestra que las ondas cuadradas generadas con realimentación positiva son más robustas frente a cambios en los valores de los parámetros que las obtenidas con realimentación negativa. Finalmente, a partir del cálculo preciso del período de las soluciones, se demuestra que el período de las soluciones se divide en diferentes valores. En el Capítulo 7, se considera el caso de OEOs no idénticos, incluyendo las posibilidades de realimentación negativa, positiva y mixta. Se demuestra que este sistema puede generar múltiples ondas cuadradas, con diferentes tipos de sincronización (en fase, en antifase y a un cuarto del período) dependiendo del signo de la realimentación de cada oscilador. Las ondas cuadradas con sincronización a un cuarto del período aparecen principalmente cuando la realimentación es negativa para un oscilador y positiva para el otro. Finalmente se analiza la robustez de las soluciones sincronizadas a un cuarto del período frente a pequeños cambios en los valores de los parámetros. La parte III se centra en el tema Sistemas fotónicos con retardos que dependen del estado y está formada per un único capítulo: En el Capítulo 8, se considera un sistema de láser de semiconductor con filtrado frecuencial desde dos cavidades de longitudes y frecuencias centrales diferentes, como prototípico para estudiar la dinámica de un sistema con retardo que depende del estado. Primero se introduce el diseño experimental, basado en un láser de semiconductor con realimentación filtrada desde dos filtros de Bragg con diferentes frecuencias centrales y situados en dos cavidades de diferetes longitudes, y por lo tanto asociados a diferentes tiempos de retardo. Se demuestra que la dinámica de este sistema se caracteriza por saltos erráticos entre los dos valores del tiempo de retardo. A continuación se introduce un modelo teórico con filtrado lorenciano desde dos cavidades diferentes. Se calculan las soluciones estacionarias y se analiza la dinámica errática con retardo que depende del estado para diferentes valores de los parámetros. Se demuestra que los resultados numéricos en el régimen errático concuerdan de forma cualitativa con los resultados experimentales. También se demuestra que este sistema tiene soluciones más regulares, similares a las ondas cuadradas, con retardo dependiente del estado. Finalmente se analiza la estadística de los tiempos de residencia durante los que el retardo toma un valor constante. La parte IV, Resumen y perspectivas de trabajo , contiene dos capítulos de conclusiones: el Capítulo 9, correspondiente a la parte de los OEOs; y el Capítulo 10, referido a la parte de sistemas fotónicos con retardos dependientes del estado. En estos capítulos, se resumen los principales resultados obtenidos y se proponen algunas perspectivas de trabajo para futuras investigaciones.
This PhD thesis focuses on the theoretical and numerical study of photonic systems with feedback from multiple delay lines, in the limit in which the delay times are much longer than the intrinsic time scales of the system. Two optical systems with feedback are considered: i) two mutually delay-coupled optoelectronic oscillators (OEOs) and ii) a semiconductor laser with a delay time that depends on the state of the system via the filtered feedback from two cavities with different length and central frequency. Although these two systems have in common the presence of multiple delay lines, they are indeed quite different. In the former, two different delay times take part at any time. In the latter, in contrast, light takes a single delay line at any time; in this system, the delay time value is intrinsically selected among two different values by the state of the system since the frequency of light is selectively filtered by using two filters of different central frequencies placed in two cavities of different lengths. On the one hand, these systems are modelled and analytical methods are developed to find approximate solutions. These methods could be used to understand the dynamics of other systems with delay. On the other hand, extensive numerical simulations are compared to analytical or experimental results. The thesis is divided into four parts. Parts I, II and IV contain several chapters, whereas part III has a single chapter. Part I, Introduction, objectives, tools and previous results , is divided in three chapters: In Chapter 1, some examples of systems in which the presence of delays determines the dynamical properties of the system, often giving rise to complex behavior, are first introduced. After that, the generic problem of a system with delay and its modelling with delay differential equations is presented. Two examples are explained in detail, including their modelling with delay differential equations. Then, the square-wave periodic regime that can be obtained with OEOs and other systems with delay is introduced, and some applications of the square-wave regime are highlighted, such as the control of the period and information encoding. The chapter ends with a summary of the objectives of the thesis. Chapter 2 introduces some analytical and numerical methods and tools used in this thesis, such as the linear stability analysis, methods and tools for the study of the stability of periodic solutions, and algorithms to integrate numerically delay differential equations. Chapter 3 is devoted to the study of the dynamics of simple systems in which the systems studied in this thesis are based: a single OEO and a semiconductor laser with optical feedback. In each case, the system is described in detail, its modelling with delay-defferential equations is introduced, and its different dynamical regimes and possible applications are presented. Part II is devoted to the Synchronization in mutually delay-coupled optoelec- tronic oscillators and contains four chapters: Chapter 4 describes the system of two mutually delay-coupled OEOs with two different delay times, the self-feedback delay time and the coupling delay time. First, the dynamical equations of the system are derived. After that, the equations are writen in non-dimensional form and the steady state (fixed point) of the system is found. Finally, the case of identical OEOs is introduced, the dynamical equations are simplified and it is shown that the linear stability analysis of the zero solution gives rise to periodic solutions synchronized in phase and out of phase. Chapter 5 focuses on the generation of symmetric square-wave pulses by the system of two identical mutually delay-coupled OEOs described in Chapter 4, in the case of negative feedback, which tends to reduce the effect of the perturbations of the steady state solution. First, linear stability analysis is applied to obtain the period of the solutions as a function of the ratio between the two different delay times. It is shown that multiple in-phase square waves with different periods can coexist when the ratio between the self-feedback and the cross-feedback delay times satisfies a rational relationship involving two odd numbers. Similarly, multiple outof- phase square waves with different periodicity can coexist when the ratio between the self- and the cross-delay times is an odd/even rational. After that, asymptotic methods are applied to obtain maps for the amplitude of the solutions. It is found that the symmetric square-wave periodic solutions undergo a period doubling route to chaos. Then, the effect of the parameter mismatch in the form of the solutions is analyzed. Finally, a splitting of the period in different values is demonstrated by performing a precise calculation of the period of the solutions. Chapter 6 is devoted to the emergence of stable square-wave pulses with the system described in Chapter 4 in the case of positive feedback, which tends to amplify the effect of the perturbations of the steady state solution. The square waves arising with positive feedback have an asymmetric duty cycle and turn out to be more flexible and robust than those obtained with negative feedback; in particular, the asymmetry of their duty cycle allows them to adapt their shape in response to changes in the parameter values instead of undergoing a period doubling. First, the linear stability analysis of the steady state is applied to obtain the period of the oscillatory solutions as a function of the two different delay times. It is shown that the system has stable in- and out-of-phase synchronized solutions, and that several solutions can coexist, similarly to the case of negative feedback. Nevertheless, in contrast to the negative feedback case, here out-of-phase solutions always coexist with in-phase solutions with different periods. Furthermore, this system has limit cycles of lower frequency, synchronized in phase and coexisting with the aforementioned fast square waves for the same values of the parameters. After that, an asymptotic method is applied to determine the amplitude and the shape of the square waves. It is shown that the duty cycle of the square waves generated with positive feedback can be tuned with the constant voltage applied to the OEOs, while the total period remains constant. The effect of the parameter mismatch on the form of the solutions is also analyzed. It is found that the square waves generated with positive feedback are more robust to parameter mismatch than those obtained with negative feedback. Finally, a splitting of the period in different values is demonstrated by performing a precise calculation of the period of the solutions. Chapter 7 addresses the case of two non-identical OEOs, including the possibilities of negative, positive, and mixed feedback. It is shown that this system can generate multiple square-wave solutions, with different kinds of synchronization (in-phase, out-of-phase, or at a quarter of the period) depending on the sign of the feedback on each oscillator. The square waves with synchronization at a quarter of the period mainly appear when the feedback is negative for one oscillator and positive for the other one. Finally, the robustness of the solutions synchronized at a quarter of the period to parameter mismatch is analyzed. Part III focuses on the topic Photonic systems with state-dependent delays and contains a single chapter: In Chapter 8, a semiconductor laser system with frequency filtering from two cavities of different lengths and central frequencies is considered as prototypical to study the dynamics of a system with state-dependent delay. First, the experimental setup is presented. It is based on a semiconductor laser with filtered feedback from two Bragg filters of different central frequencies placed in two cavities of different lengths, and thus associated to different delay times, experiencing erratic jumps between the two delay-time values. Then, a theoretical model with lorentzian filtering from different cavities is introduced. The stationary solutions are calculated and the erratic dynamics with state-dependent delay is analyzed for different parameter values. It is shown that numerical results in the erratic regime are in qualitative agreement with the experiments. It is also shown that this system has more regular solutions, similar to the square waves, with state-dependent delay. Finally, the switching statistics is analyzed from the residence times during which the delay time remains constant. Part IV, Summary and future work , contains two concluding chapters: Chapter 9, corresponding to the part of OEOs; and Chapter 10, associated to the part of photonic systems with state-dependent delays. In these chapters, the main results are summarized and some perspectives of future work are proposed.

Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2012.
Cataloged from PDF version of thesis.
Includes bibliographical references (p. 73-75).
A new continuous-time multi-stage noise-shaping delta-sigma modulator has been designed. This modulator provides high resolution and robust stability characteristics which are the primary advantages of the conventional multi-stage noise-shaping architecture. At the same time, previous critical challenges that degraded the overall performance of multi-stage noise-shaping delta-sigma modulators are eliminated through several unique techniques. Additionally, these techniques relax the requirements of each component of the proposed delta-sigma modulator. As a result, this new delta-sigma modulator architecture can provide several advantages that are not obtainable in other modulator architectures.
by Do Yeon Yoon.
S.M.

A general analysis of the photon and lepton polarizations in the rare Bs &
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l+l- decay by using the most general model independent form of the effective Hamiltonian is presented. The total and the differential branching ratios for these decays, when photon is in the positive and negative helicity states, are studied. The sensitivity of "
photon polarization asymmetry"
and the longitudinal, transverse and normal polarization asymmetries of final state leptons, as well as lepton-antilepton combined asymmetries in Bs &
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l+l- decay to the new Wilson coefficients are also investigated. It is shown that all these physical observables are very sensitive to the existence of new physics beyond SM and their experimental measurements can give valuable information about it.

Thesis (M. Phil.)--Hong Kong University of Science and Technology, 2003.
Includes bibliographical references (leaves 77-79). Also available in electronic version. Access restricted to campus users.

Orientador: Cláudia Pio Ferreira
Abstract: This thesis presents two manuscripts previously sent to publication in scientific journals. In the first manuscript, a delay differential equation model is developed to study the dynamics of two Aedes aegypti mosquito populations: infected by the intracellular bacteria Wolbachia and non-infected (wild) individuals. All the steady states of the system are determined, namely extinction of both populations, extinction of the infected population and persistence of the non-infected one, and coexistence. Their local stability is analyzed, including Hopf bifurcation, which promotes periodic solutions around the nontrivial equilibrium points. Finally, one investigates the global asymptotic stability of the trivial solution. In the second manuscript, after rearing soybean looper Chrysodeixis includens in laboratory conditions, thermal requirements for this insect-pest are estimated, from linear and nonlinear regression models, as well as the intrinsic growth rate. This parameter depends on the life-history traits and can provide a measure of population viability of the species.
Doutor

The two processes of outbreak identification and disease modelling are fundamental in the study of disease outbreaks affecting livestock and wildlife. Rapid detection and the implementation of appropriate preventative or control measures from an understanding of the mechanisms of disease spread may limit the impact of an outbreak. The performance of several on-line warning algorithms in their ability to detect outbreaks in both real-life and simulated data is investigated. A version of Farrington's well established outbreak detection algorithm, referred to as the EDS scheme is compared to approaches based on the Kalman Filter, namely a Prediction Interval approach and three types of CUSUM scheme. All the schemes are able to successfully identify outbreaks and we find that no single approach appears to outperform the others in all the measures considered. However the EDS scheme is the most efficient in detecting outbreaks promptly and one of the CUSUM schemes is best at producing consistent warnings throughout the outbreak period. In addition we formulate deterministic models describing the transmission dynamics of the midge-borne disease bluetongue, with cattle and sheep as hosts. The models take the form of delay differential equations and incorporate the incubation time of bluetongue in cattle, sheep and midges, and also the larval developmental time of midges. An autonomous model assuming midges to be active year round and a periodic model allowing midge activity to vary with the seasons are analysed. The transmission of the disease via midge diffusion and migration is studied in detail and the effects of vaccination are also considered. Important findings include the need for prompt diagnosis of latent infection and appropriate action before the animal becomes infectious, and the need for measures that reduce insect bites. This reinforces the importance of timely identification of disease outbreaks in order for effective intervention to be possible.

Abstract This thesis describes the development of a high precision time-to-digital converter (TDC) in which the conversion is based on a counter and three-stage stabilised delay line interpolation developed in this work. The biggest design challenges in the design of a TDC are related to the fact that the arrival moment of the hit signals (start and stop) is unknown and asynchronous with respect to the reference clock edges. Yet, the time interval measurement system must provide an immediate and unambiguous measurement result over the full dynamic range. It must be made sure that the readings from the counter and the interpolators are always consistent with very high probability. Therefore, the operation of the counter is controlled with a synchronising logic that is in turn controlled with the interpolation result. Another synchronising logic makes it possible to synchronise the timing signals with multiphase time-interleaved clock signals as if the synchronising was done with a GHz-level clock, and enables multi-stage interpolation. Multi-stage interpolation reduces the number of delay cells and registers needed. The delay line interpolators are stabilised with nested delay-locked loops, which leads to good stability and makes it possible to improve single-shot precision with a single look-up table containing the integral nonlinearities of the interpolators measured at the room temperature. A multi-channel prototype TDC was fabricated in a 0.6 μm digital CMOS process. The prototype reaches state-of-the-art rms single-shot precision of better than 20 ps and low power consumption of 50 mW as an integrated TDC.

In this thesis we consider the traditional Van der Pol Oscillator with a forcing dependent on a delay in feedback. The delay is taken to be a nonlinear function of both position and velocity which gives rise to many different types of bifurcations. In particular, we study the Zero-Hopf bifurcation that takes place at certain parameter values using methods of centre manifold reduction of DDEs and normal form theory. We present numerical simulations that have been accurately predicted by the phase portraits in the Zero-Hopf bifurcation to confirm our numerical results and provide a physical understanding of the oscillator with the delay in feedback.

Cette thèse est consacrée à l'étude d'une classe d'équations différentielles à retard dépendant de l'état -- ces équations provenant d'un modèle structuré en taille. La principale motivation de cette thèse provient de la volonté d'ajuster les paramètres du système d'équations étudiées vis-à-vis des données générées par un simulateur de forêts, appelé SORTIE. Deux types de forêts sont étudiés ici: d'une part une forêt ne comportant qu'une seule espèce d'arbre, et d'autre part une forêt comportant deux espèces d'arbres (au chapitre 2). Les simulations numériques du système d'équations correspondent relativement bien aux données générées par SORTIE, ce qui montre que le système considéré peut être utilisé afin d'écrire la dynamique de populations d'une forêt. De plus, un modèle plus étendu prenant en compte la position spatiale des arbres est proposé dans le chapitre 2, dans le cas de forêts possédant deux espèces d'arbres. Les simulations numériques de ce modèle permettent de visualiser la propagation spatiale des forêts. Les chapitres 3 et 4 se concentrent sur l'analyse mathématique des équations différentielles à retard considérées. Les propriétés du semi-flot associé au système sont étudiées au chapitre 3, où l'on démontre en particulier que ce semi-flot n'est pas continu en temps. Le caractère dissipatif et borné du semi-flot, pour des modèles de forêts comportant une ou deux espèces d'arbres, est étudié dans le chapitre 4. En outre, afin d'étudier la dynamique de population d'une forêt (d'une seule espèce d'arbre) après l'introduction d'un parasite, nous construisons dans le chapitre 5 un système proie-prédateur dont la proie (à savoir la forêt) est modélisée par le système d'équations différentielles à retard dépendant de l'état étudié auparavant, et dont le prédateur (à savoir le parasite) est modélisé par une équation différentielle ordinaire. De nombreuses simulations numériques associées à différents scénarios sont faites, afin d'explorer le comportement complexe des solutions du au couplage proie-prédateur et les équations à retard dépendant de l'état
This thesis is devoted to the studies of a class of state-dependent delay differential equations. This class of equations is derived from a size-structured model.The motivation comes from the parameter fittings of this system to a forest simulator called SORTIE. Cases of both single species forest and two-species forest are considered in Chapter 2. The numerical simulations of the system correspond relatively very well to the forest data generated by SORTIE, which shows that this system is able to be used to describe the population dynamics of forests. Moreover, an extended model considering the spatial positions of trees is also proposed in Chapter 2 for the two-species forest case. From the numerical simulations of this spatial model one can see the diffusion of forests in space. Chapter 3 and 4 focus on the mathematical analysis of the state-dependent delay differential equations. The properties of semiflow generated by this system are studied in Chapter 3, where we find that this semiflow is not time-continuous. The boundedness and dissipativity of the semiflow for both single species model and multi-species model are studied in Chapter 4. Furthermore, in order to study the population dynamics after the introduction of parasites into a forest, a predator-prey system consisting of the above state-dependent delay differential equation (describing the forest) and an ordinary differential equation (describing the parasites) is constructed in Chapter 5 (only the single species forest is considered here). Numerical simulations in several scenarios and cases are operated to display the complex behaviours of solutions appearing in this system with the predator-prey relation and the state-dependent delay

In this thesis the following model state dependent delay differential equation is considered,epsilon.u'(t) = mu.u(t) + sigma.u(t-a-c.u(t)).For fixed epsilon, a and c, the analytical stability region of this equation is known and it is the same for both the constant delay (c=0) and state dependent delay (c nonzero) cases. Different approaches are used to directly prove stability in parts of this analytic region for the state dependent DDE: first using a Gronwall argument and then using a Lyapunov-Razumikhin method which is a generalisation of the work of Barnea [6] who considered the mu=c=0 case. The parameter regions in which stability is proven by these methods contain the entire delay independent portion of the analytical stability region and parts of the delay dependent portion. These methods are then extended to show the stability of the backward Euler method with linear interpolation applied to the model DDE. Using the Lyapunov-Razumikhin method, stability is proven in larger parameter regions that depend on the stepsize, but always contain the region found for the DDE. Analytic expressions for regions in which general Theta methods are stable were also derived and evaluated numerically. In the last chapter a new scheme for numerically integrating scalar DDEs with multiple state dependent delays is presented. This scheme is based on singularly diagonally implicit Runge-Kutta (SDIRK) methods in order to solve stiff problems such as the equation above with small epsilon. Due to the nature of SDIRK methods, if there is no overlapping then at each step a set of scalar equations are solved one-by-one using a Newton-bisection algorithm. New continuous extensions which are piecewise polynomial are chosen to accompany the SDIRK scheme so as not to destroy the SDIRK structure in the overlapping cases and to avoid the problem of spiking when there is a sharp change in the numerical solution.
Dans cette thèse, l'équation différentielle à retard (DDE) modèle d'état dépendant suivante est considérée,epsilon.u'(t) = mu.u(t) + sigma.u(t-a-c.u(t)).Pour epsilon, a et c fixés, la région de stabilité analytique de cette équation est connue et est la même pour le retard constant (c=0) ainsi que pour l'état de retard dépendant (c non nulle). Différentes approches sont utilisées pour prouver directement la stabilité dans certaines parties de cette région analytique pour la DDE d'état dépendant: d'abord en utilisant un argument de Gronwall, puis en utilisant une méthode de Lyapunov-Razumikhin qui est une généralisation du travail de Barnea [6] qui considère le cas mu = c = 0. Les régions de paramètres dans lesquelles la stabilité est prouvée par ces méthodes contiennent la partie entière de retard indépendant de la région de stabilité analytique et certaines parties de la portion de retard dépendant. Ces méthodes sont ensuite étendues pour montrer la stabilité de la méthode d'Euler arrière avec interpolation linéaire appliquée à la DDE modèle. En utilisant la méthode de Lyapunov-Razumikhin, la stabilité est prouvée dans des regions de paramètres plus grandes qui dépendent du pas de discrétisation, mais qui contiennent toujours la région trouvée pour la DDE. Des expressions analytiques pour les régions dans lesquelles les méthodes Theta générales sont stables ont également été tirées et évaluées numériquement. Dans le dernier chapitre d'un nouveau schéma pour intégration numérique des DDE scalaires avec des multiples retards d'état dépendant est présenté. Ce schéma est basé sur des méthodes de Runge-Kutta singulièrement et diagonalement implicites (SDIRK) afin de résoudre des problèmes raides tels que l'équation ci-dessus avec des petites valeurs de epsilon. En raison de la nature des méthodes SDIRK, s'il n'y a pas de chevauchement, alors à chaque iteration un ensemble d'équations scalaires sont résolues, une par une, en utilisant un algorithme de bissection de Newon. Des nouvelles extensions continues qui sont polynomiales par morceaux sont choisies pour accompagner le schéma SDIRK afin de ne pas détruire la structure SDIRK dans les cas de chevauchement et pour éviter le problème des piques quand il y a un changement brusque de la solution numérique.

This research examined the effects of two aspects of health state context, etiology and delay in onset, on preferences for health states. Research questions about the effect of etiology were derived from regret theory and prospect theory, theories of behavioral decision making: (1) Does etiology (iatrogenic versus natural) affect utility for a health state? (2) Does framing iatrogenic morbidity as a transaction cost reduce its disutility? Research questions about delayed health outcomes were based on the theory of intertemporal choice: (1) Does time preference for health differ for health gains and losses? (2) Does the time preference difference between gains and losses apply to both short and long-term changes in health? Each contextual factor was investigated in a separate mixed factorial experimental design. Subjects were randomly assigned to rate three hypothetical health states described in one of three frames: unexplained loss of health, iatrogenic loss of health, or iatrogenic cost of overall health gain, and to evaluate either health gain or loss profiles in which the duration and delay of onset of the health change were manipulated. One hundred and eight volunteers were obtained from a university staff population, and outpatient and volunteer populations of a Veterans Affairs hospital. Data for both studies were collected in one hour interviews. Utilities for health states and health profiles were assessed with the standard gamble and the category rating scale respectively. Inferential tests of hypotheses were based on mixed factorial analyses of variance. In the framing study hypotheses were tested with planned comparison t tests; in the time preference study they were tested with F tests of double and triple interactions. Conclusions were that greater disutility is assigned to iatrogenic morbidity than to natural morbidity, that time preference for health gains differs from time preference for losses, and that devaluation of a delayed health loss is dependent on its duration. The theory of intertemporal choice was supported in the health domain. Conclusions cannot be extended beyond preferences elicited with hypothetical health scenarios. Lack of support for a framing effect for iatrogenic health states was attributed to inadequate statistical power.

NEMO 3 is a double beta decay experiment situated in the Fréjus tunnel which runs between France and Italy. If neutrinoless double beta decay is observed it will prove the neutrino is a Majorana particle and may potentially become the most sensitive method of measuring the absolute neutrino mass. It would also have huge implications for not only particle physics, but also nuclear physics, astrophysics and cosmology. The study of two-neutrino double beta decay gives us a better understanding of the nuclear models used to calculate the nuclear matrix elements, which are so important in extracting new physics parameters from the neutrinoless double beta decay search. The purpose of this thesis is primarily to report on the measurement of the two neutrino double beta decay of two isotopes, ^{100}Mo and ^{48}Ca, currently inside the NEMO 3 detector. The double decay of ^{100}Mo to the O^{+}_{1} excited state of ^{100}Ru is studied as well as the double beta decay of ^{48}Ca to the ground state of ^{48}Ti. The two neutrino half-life measurement for ^{100}Mo is found to be T^{2\upsilon}_{1/2}(O^+\rightarrow O^{+}_1}) = 5.70^{+1.15}_{-0.82} (stat) \pm 0.77 (syst.) \times 10^{20} yrs. This being the first result where all the final states have been measured. For ^{48}Ca, the two neutrino half-life is T^{2\upsilon}_{1/2}(g.s. \rightarrow g.s.) = 4.44^{+0.49}_{-0.40}(stat.) \pm 0.29 (syst.) \times 10^{19} yrs, which is the worlds most accurate measurement of this decay process. A limit on the neutrinoless double beta decay of ^{48}Ca has also been obtained.

Results are presented of a search for the Standard Model (SM) Higgs boson decaying into two photons at the Compact Muon Solenoid (CMS) experiment housed at the Large Hadron Collider (LHC), CERN. An excess of events is observed over the background expectation with a local significance of 5.7 (lower-case sigma), where the SM expectation is 5.2 (lower-case sigma), constituting a standalone discovery of the particle first observed by the ATLAS and CMS experiments in July 2012. Measurements of the particle's signal strength, mass and couplings are presented along with an analysis of its spin. The results show a high level of compatibility with the predictions for a SM Higgs boson. The observed state's signal strength relative to the SM expectation is found to be lower-case sigma/lower-case sigma_{\mathrm{SM}}=1.14^{+0.26}_{-0.23}$. The observed state's mass is found to be $124.72\pm 0.35$~GeV. The signal strength relative to the SM expectation when probing production mechanisms through fermionic modes only is 1.13^{+0.37}_{-0.31}, and from bosonic production modes only is 1.16^{+0.63}_{-0.57}. A spin-2 graviton, produced entirely by gluon fusion, is excluded at 94\%~C.L.~(92\% expected) and a spin-2 graviton, produced entirely by quark-antiquark annihilation, is excluded at 85\%~C.L.~(83\% expected).

Cette thèse répond une étude de la η c (1S) d'état de charmonium utilisant désintégrations à l'état final proton-antiproton à l'expérience LHCb. La section efficace de production du méson η c dans les interactions parton et dans les désintégrations b-hadrons sont signalés. La production de l'état η c (1S) est mesurée par la désintégration de ppbar avec le détecteur LHCb, en utilisant une luminosité intégrée de 0,7 fb⁻¹ accumulé à 7 TeV l'énergie de centre de masse en 2011, et une luminosité intégrée de 2 fb⁻¹ accumulé à 8 TeV l'énergie de centre de masse en 2012 les mesures sont effectuées en utilisant le J / ψ → ppbar décroissance comme un canal de référence. Haut de centre de masse des énergies disponibles dans les collisions proton-proton au LHC permet modèles décrivant la production de charmonium à tester. Nous distinguons rapidement présenté charmonia de ceux provenant de b-hadron se désintègre. Rapidement produites charmonia comprennent charmonia produit directement dans les interactions parton et ceux provenant de la désintégration de lourdes Etats quarkonium, qui sont à leur tour produit dans les interactions de partons. Production de charmonium invite comprend la production directe de l'interaction de parton et charmonium provenant de désintégrations des etats les plus lourds. Le taux relatif de la production rapide de l'etats η c et J / ψ dans l'acceptation LHCb (gamme de rapidité 2,0 6,5 GeV/c est mesurée pour la première le temps d'être σ (η c) / σ (J / ψ) = 1,74 ± 0,29 ± 0,28 stat syst ± 0,18 B l'énergie de centre de masse 7 TeV, et σ (η c) / σ (J / ψ) = 1,60 ± 0,29 stat ± 0,25 ± 0,17 syst B l'énergie de centre de masse 8 TeV. Utilisation du J / ψ section efficace de production mesurée par LHCb et en supposant qu'aucun J / ψ polarisation, l'absolu η c section efficace de production dans le même régime cinématique est σ η c = 0,52 ± 0,09 ± 0,08 stat syst ± 0,06 σ J / ψ, B l'énergie de centre de masse 7 TeV, et σ η c = 0,59 ± 0,11 stat ± 0,09 ± 0,08 syst σ J / ψ, B l'énergie de centre de masse 8 TeV. La troisième composante d'erreur correspond à l'incertitude de la J / ψ → p et η c → p ramification fractions et la mesure de section eficase J/ψ. Le rapport η c à J/ψ compris fraction de branchement de b-hadron désintégrations est mesuré pour être B (b → η c X) / B (b → J / ψ X) = 0,42 ± 0,06 ± 0,02 stat syst ± 0,05 B. Utilisation de l'J/ψ compris fraction ramification de b-hadron désintégrations mesuré avec le J/ψ →μμ canal de désintégration, l'inclusion η c ramification fraction de b-hadron désintégrations se trouve être B (b → η c X) = (4,9 ± 0,6 ± 0,3 stat syst ± 0,7 B) × 10 ⁻³, où la troisième composante d'erreur correspond à l'incertitude dans les J/ψ → pp et η c → pp ramification fractions (et le J/ψ compris fraction J ramification de b-hadron décroît). La mesure de la fraction η c de branchement inclus rapport de b-hadron se désintègre est la plus précise à ce jour. Utilisation de l'échantillon à faible fond de η c de b-hadron se désintègre, la différence de masse J / ψ et η c, ΔMJ / ψ, η c = 114,7 ± 1,5 ± 0,1 MeV / c², est mesurée. La valeur de la production par rapport compris η c J/ψ est important de faire la distinction entre une grande variété de modèles théoriques. Le η c section est mesurée dans des bacs de dynamique transversale. Il présente un comportement similaire à ceux obtenus dans l'analyse de la production J/ψ, mais avec beaucoup plus importantes incertitudes. Les limites supérieures sur la production de certains autres états charmonium sont adressées
This thesis addresses a study of the η c (1S) charmonium state using decays to proton-antiproton final state at the LHCb experiment. The production cross-section of the η c meson in parton interactions and in b-hadron decays are reported. Production of the η c (1S) state is measured via the decay to ppbar with the LHCb detector, using an integrated luminosity of 0.7 fb⁻¹ accumulated at 7 TeV centre-of-mass energy in 2011, and an integrated luminosity of 2 fb⁻¹ accumulated at 8 TeV centre-of-mass energy in 2012. The measurements are performed using the J/ψ → ppbar decay as a reference channel. High centre-of-mass energies available in proton-proton collisions at the LHC allow models describing charmonium production to be tested. We distinguish promptly produced charmonia from those originating from b-hadron decays. Promptly produced charmonia include charmonia directly produced in parton interactions and those originating from the decays of heavier quarkonium states, which are in turn produced in parton interactions. Prompt charmonium production comprises direct production in the parton interaction and charmonium originating from decays of heavier states. The relative rate of prompt production of the η c and J/ψ states in the LHCb acceptance (rapidity range 2.0 < y < 4.5) and for p T (J/ψ , η c ) > 6.5 GeV/c is measured for the first time to be σ (η c) /σ (J/ψ) = 1.74 ± 0.29 stat ± 0.28 syst ± 0.18 B at a centre-of-mass energy 7 TeV, and σ (η c) /σ (J/ψ) = 1.60 ± 0.29 stat ± 0.25 syst ± 0.17 B at a centre-of-mass energy s = 8 TeV. Using the J/ψ production cross-section measured by LHCb and assuming no J/ψ polarization, the absolute η c prompt production cross-section in the same kinematic regime is found to be σ η c = 0.52 ± 0.09 stat ± 0.08 syst ± 0.06 σ J/ψ , B at a centre-of-mass energy 7 TeV, and σ η c = 0.59 ± 0.11 stat ± 0.09 syst ± 0.08 σ J/ψ , B at a centre-of-mass energy s = 8 TeV. The third error component corresponds to the uncertainty in the J/ψ → pp and η c → pp branching fractions and the J/ψ cross-section measurement. The relative η c to J/ψ inclusive branching fraction from b-hadron decays is measured to be B(b→η c X) /B(b→J/ψ X) = 0.42 ± 0.06 stat ± 0.02 syst ± 0.05 B. Using the J/ψ inclusive branching fraction from b-hadron decays measured with the J/ψ → μμ decay channel, the inclusive η c branching fraction from b-hadron decays is found to be B(b→η c X) = (4.9 ± 0.6 stat ± 0.3 syst ± 0.7 B) × 10 ⁻³ ,where the third error component corresponds to the uncertainty in the J/ψ → pp and η c → pp branching fractions (and the J/ψ inclusive branching fraction from b-hadron decays). The measurement of the relative η c inclusive branching fraction from b-hadron decays is the most precise to date. Using low-background sample of η c from b-hadron decays, the J/ψ and η c mass difference, ∆M J/ψ , η c = 114.7 ± 1.5 ± 0.1 MeV/c² , is measured. The value of the relative inclusive η c production to J/ψ is important for distinguishing between a variety of theoretical models. The η c cross-section is measured in bins of transverse momentum. It exhibits a similar behaviour to those obtained in the J/ψ production analysis, though with significantly larger uncertainties. The upper limits on the production of some other charmonium states are addressed

Thesis (M.S.)--University of Missouri-Columbia, 2007.
The entire dissertation/thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file (which also appears in the research.pdf); a non-technical general description, or public abstract, appears in the public.pdf file. Title from title screen of research.pdf file (viewed on January 7, 2008) Includes bibliographical references.

The Higgs self-coupling has a vital role by giving a deeper understanding of the Higgs particle. Furthermore, the way it opens to physics beyond the SM, encourages us to do MC simulationstudies for varying λ_hhh . In this project, we investigate the effects of choosing different values for λ_hhh on the kinematics of all particles involved in the hh → τ τ τ τ decay channel and the resultsare compared with what we get from the SM prediction of λ_hhh .The data show that λ_hhh more close to the SM trilinear Higgs self-coupling results in generatingthe Higgs particles with the higher masses and higher momenta. On the other hand, for the moremassive Higgs bosons we have more energetic neutrinos in the final states which escape from thedetector without being detected.

With the relentless shrinking of the minimum feature size of VLSI Integrated Circuits (ICs), reduction in operating voltages and increase in operating frequencies, VLSI circuits are becoming more vulnerable to radiation strikes. As a result, this problem is now important not only for space and military electronics but also for consumer ICs. Thus, the design of radiation-hardened circuits has received significant attention in recent times. This thesis addresses the radiation hardening issue for VLSI ICs. In particular, circuit techniques are presented to protect against Single Event Transients (SETs). Radiation hardening has long been an area of research for memories for space and military ICs. In a memory, the stored state can ip as a result of a radiation strike. Such bit reversals in case of memories are known as Single Event Upsets (SEUs). With the feature sizes of VLSI ICs becoming smaller, radiation-induced glitches have become a source of concern in combinational circuits also. In combinational circuits, if a glitch due to a radiation event occurs at the time the circuit outputs are being sampled, it could lead to the propagation of a faulty value. The current or voltage glitches on the nodes of a combinational circuit are known as SETs. When an SET occurring on a node of a logic network is propagated through the gates of the network and is captured by a latch as a logic error, it is transformed to an SEU. The approach presented in this thesis makes use of Code Word State Preserving (CWSP) elements at each ip-op of the design, along with additional logic to trigger a recomputation in case a SET induced error is detected. The combinational part of the design is left unaltered. The CWSP element provides 100% SET protection for glitch widths up to min{(Dmin-D1)/2, (Dmax-D2)/2}, where Dmin and Dmax are the minimum and maximum circuit delay respectively. D1 and D2 are extra delays associated with the proposed SET protection circuit. The CWSP circuit has two inputs - the flip flop output signal and the same signal delayed by a quantity 6. In case an SET error is detected at the end of a clock period i, then the computation is repeated in clock period i+1, using the correct output value, which was captured by the CWSP element in the ith clock period. Unlike previous approaches, the CWSP element is i) in a secondary computational path and ii) the CWSP logic is designed to minimally impact the critical delay path of the design. It was found through SPICE simulations that the delay penalty of the proposed approach (averaged over several designs) is less than 1%. Thus, the proposed technique is applicable for high-speed designs, where the additional delay associated with the SET protection must be kept at a minimum.

Le détecteur NEMO3 a été conçu pour l'étude de la double désintégration bêta et particulièrement pour la recherche de la double désintégration bêta sans émission de neutrino ($0\nu\beta\beta$). La sensibilité attendue pour la désintégration $0\nu\beta\beta$ est, en terme de la demi-vie de l'ordre de $10^(25)$~ans, en terme de masse effective du neutrino cela correspond à une sensibilité (0,3 -- 0,1)~eV. Le processus $0\nu\beta\beta$ représente aujourd'hui le test de la nature Majorana du neutrino le plus prometteur. Le détecteur a été construit au Laboratoire Souterrain de Modane (LSM) en France par la collaboration internationale (France, Russie, République Tchèque, États-Unis, Royaume-Uni, Finlande et Japon). La prise de donnée a commencé en mai 2002 et continue actuellement. La masse de $^(100)$Mo dans le détecteur (7~kg) permet une mise en évidence de la double désintégration bêta avec émission de deux neutrinos ($2\nu\beta\beta$) du $^(100)$Mo vers l'état excité $0^+_1$ (canal eeN$\gamma$). Les simulations Monte-Carlo de l'effet et de tous les types de bruit de fond ont été effectuées pour définir un ensemble des critères de sélection appropriés. D'autre part des runs avec des sources du $^(208)$Tl et du $^(214)$Bi ainsi que des simulations Monte-Carlo de ces données ont montré que le seul bruit de fond significatif dans le canal eeN$\gamma$ vient du radon qui avait pénétré à l'intérieur de la chambre à fils de NEMO3. Les données expérimentales acquises de mai 2002 à mai 2003 ont été analysées pour déterminer le signal dû à la désintégration $2\nu\beta\beta$ du $^(100)$Mo vers l'état excité $0^+_1$ et le niveau de bruit de fond correspondant. Le résultat est donné sous la forme d'un intervalle de valeurs de la demi-vie au niveau de 95\% de confiance. Cela correspond à une mise en évidence du processus au niveau de confience de quatre écarts standards.

The CUORE experiment is the largest bolometric array ever built with the main goal of searching for the lepton number violating neutrinoless double beta decay of 130Te. The closely packed arrangement of the CUORE crystals allows us to look for coincident signals between detectors. The latest results on neutrino-less double beta decay search of 130Te to the ground 0+1 state of 130Xe and first 0+2 excited state will be presented and discussed. The presence of de-excitation gammas in the final state helps reducing the background by studying coincident events in two or more bolometers. The Standard Model 2νββ decay channel of the same isotope on the 0+2 excited state of 130Xe will be investigated as well. No evidence for any of the mentioned decay modes was observed and a Bayesian upper bound at 90 % C.I. on the decay rate will be presented and discussed.

This work investigates the development, applications and stability analysis of a biologically-based dose-response model for developmental toxicology. The biologically-based controlled growth and differentiation model is based on a model originally developed by Leroux et al. (1996). The original model had two basic states; precursor cells and differentiated cells with both states subject to a linear birth-death process. The research discussed in this dissertation describes the development of a mathematical model that is both biologically- and statistically-based. The model is developed with a highly controlled birth and death process for precursor cells. This model limits the number of replications allowed in the development of a tissue or organ and more closely reflects the presence of a true stem cell population. The mathematical formulation of the Leroux et al. (1996) model was derived from a partial differential equation for the generating function that limits further expansion into more realistic models of mammalian development. The same formulae for the probability of a defect (a system of ordinary differential equations) can be derived through the Kolmogorov forward equations due to the nature of this Markov process. This modified approach is easily amenable to the expansion of more complicated models of the developmental process. Comparisons between the Leroux et al. (1996) model and the controlled growth and differentiation (CGD) model are also discussed.The versatility of the CGD model is highlighted through a discussion of two general applications. The normal developmental process of spermatocytogenesis is investigated as the first application. Time delays are introduced into the system to more accurately mimic the development of male germ cells. As the second application, the spermatocytogenesis model is then altered to demonstrate a modeling strategy for hormesis. Asymptotic stability is investigated using the system of delay differential equations for spermatocytogenesis. The direct Lyapunov method for linear differential equations without delay is modified to establish delay-dependent stability conditions for delay differential equations with multiple delays. The stability conditions are expressed in terms of the existence of a positive definite solution to the Riccati matrix equations. Numerical simulations further verify the stability conditions.

In this paper, we identify sufficient conditions for Lyapunov Mean Square Stability (LMSS) of a contention-based network of first-order systems, with state-based schedulers. The stability analysis helps us to choose policies for adapting the scheduler threshold to the delay from the network and scheduler. We show that three scheduling laws can result in LMSS: constant-probability laws and additively increasing or decreasing probability laws. Our results counter the notions that increasing probability scheduling laws alone can guarantee stability of the closed-loop system, or that decreasing probability scheduling laws are required to mitigate congestion in the network.

QC 20130116

Bioreactors are used to carry out bioprocesses and are commonly used in e.g. biogas production and wastewater treatment. Two common hydraulic models of bioreactors are the continuous stirred tank reactor (CSTR) and the plug-flow reactor (PFR). In this paper, a differential equation system that describes the substrate, biomass and inert biomass in the bioreactors is presented. It is used in a steady-state analysis and design of CSTRs in series. Monod kinetics were used to describe the specific growth rate and the decay of biomass was included. Using the derived systems of differential equations, two optimization problems were formulated and solved for both CSTRs in series and for a CSTR+PFR. The first optimization problem was to minimize the effluent substrate level given a total volume, and the second was to minimize the total volume needed to obtain a certain substrate conversion. Results show that the system of differential equations presented can be used to find optimal volume distributions that solves the optimization problems. The optimal volume for N CSTRs in series decreases as N increases, converging towards a configuration of a CSTR followed by a PFR. Analyzing how the decay rate affects the results showed that when the total volume was kept constant, increasing the decay rate caused less difference between the configurations. When the total volume was minimized, increasing the decay rate caused the configurations to diverge from each other. The presented model can be used to optimally divide reactors into smaller zones and thereby increasing the substrate conversion, something that could be of interest in e.g. existing wastewater treatment plants with restricted space. A fairly accurate approximation to the optimal design of N CSTRs in series is to use the optimal volume for the CSTR in the configuration with a CSTR+PFR and equally distribute the remaining volumes.
Bioreaktorer används för att utföra olika biologiska processer och används vanligen inom biogasproduktion eller för rening av avloppsvatten. Två vanliga hydrauliska modeller som används vid modellering av bioreaktorer är helomblandad bioreaktor (på engelska continuous stirred tank reactor, CSTR) eller pluggflödesreaktor (på engelska plug-flow reactor, PFR). I den här rapporten presenteras ett system av differentialekvationer som används för att beskriva koncentrationerna av substrat, biomassa och inert biomassa i både CSTR och PFR. Ekvationssystemet används för analys och design av en serie CSTRs vid steady-state. Tillväxten av biomassa beskrivs av Monod-kinetik. Avdödning av biomassa är inkluderat i studien. Från ekvationssystemet formulerades två optimeringsproblem som löstes för N CSTRs i serie och för CSTR+PFR. Det första optimerinsproblemet var att minimera substrathalten i utflödet givet en total volym. I det andra minimerades den totala volymen som krävs för att nå en viss substrathalt i utflödet. Resultaten visade att ekvationssystemet kan användas för att hitta den optimala volymsfördelningen som löser optimeringsproblemen. Den optimala volymen för N CSTRs i serie minskade när antalet CSTRs ökade. När N ökade konvergerade resultaten mot de för en CSTR sammankopplad med en PFR. En analys av hur avdödningshastigheten påverkade resultaten visade att en ökad avdödningshastighet gav mindre skillnad mellan de två olika konfigurationerna när den totala volymen hölls konstant. När den totala volymen istället minimerades ledde en ökad avdödningshastighet till att de två konfigurationerna divergerade från varandra. Modellen som presenteras i studien kan användas för att fördela en total reaktorvolym i mindre zoner på ett optimalt sätt och på så vis öka substratomvandlingen, något som kan vara av intresse i exempelvis befintliga avloppsreningsverk där utrymmet är begränsat. En relativt bra approximation till den optimala designen av N CSTRs i serie är att optimera volymerna för en CSTR+PFR, använda volymen för CSTR som första volym i konfigurationen med N CSTR i serie, och sedan fördela den kvarvarande volymen lika mellan de övriga zonerna.

Women of child-bearing age sometimes fail to plan for pregnancies. Often they discover that they are pregnant and are not prepared or cannot afford to raise the child. Before 1996 there was no choice for women as regards pregnancies, all pregnancies must be carried to term and delivered except on health grounds and with stringent conditions. However after the TOP act was enacted in 1996, women were allowed a choice of TOP up to and including 20 weeks of pregnancy.

Regardless of the availability of choice of TOP, some pregnant women still present late (after 12 weeks) for TOP when the risks of complications and costs are higher. Women who present late for TOP usually have to be admitted to a district or regional hospital and managed. The costs at such institutions are high. TOPs before 12 weeks (early TOP) are done in a primary health care (PHC) facility (TOP center) and no admission is required hence less cost. Complications of early TOP are also very mild and rare. In Lejweleputswa district there is only one TOP Center (Kopano TOP Clinic) and this serves both Lejweleputswa and the Northern Free State districts. Early TOPs (less than 12 weeks) are done and completed at this center. Late TOPs (above 12 weeks but not more than 20 weeks) are initiated at this TOP center and referred to district or regional hospitals nearest to the patient&rsquo
s home, in both districts for completion.

Problems - An increasing number of women are seeking TOP service at late stages of pregnancies and the incidence of severe complications like severe bleeding, retained placenta, infection, amniotic fluid embolism, death etc, are increasing. The hospital&rsquo
s bed space and budget are stretched to the limit due to the influx of late term TOP to the hospitals. Lack of manpower, especially doctors, in these hospitals also create some problems, as the few doctors available have to attend to other ill patients as well. Sometimes bleeding TOP patients are transfused with blood and placed on a waiting list for theatre and this often increases the risk of complications. The emotional effect of late TOP on hospital staff (doctors and nurses) are enormous as the expelled fetus are much more developed than in early TOP where no fetus is seen at evacuation with simple Manual Vacuum Aspiration (MVA).