Background: Asthma is a heterogeneous disease. Diagnosis relies on symptom evaluation and lung function tests using spirometry. Symptoms can be vague. Spirometry is effort-dependent and does not reliably evaluate small airways. Allergic asthma in preschool children is not easily separated from episodic wheeze. Exhaled NO (FeNO) is a marker of allergic Th2-cytokine-driven airway inflammation. However, FeNO is not feasible in preschoolers with current devices and algorithms. Alveolar NO is an estimate of small airway involvement. Forced oscillometry (FOT) is an effort-independent lung function test assessing both large and small airways. Aims: To study clinical and methodological aspects of FeNO, alveolar NO and lung function indices by FOT. Methods: Asthmatic children and young adults and healthy controls, were included in the studies. FeNO at 50 mL/s was performed in all studies (in study III with an adapted single-breath method with age-adjusted exhalation times). FeNO at multiple exhalation flow rates were performed in studies I, II and IV to calculate alveolar NO, as was spirometry. FOT indices were assessed in study IV. Results: The exhalation time needed to reach steady-state NO was < 4 s in subjects aged 3-4 years, and was related to subject height. FeNO was higher in ICS-naïve asthmatic children than in controls. ICS-naïve asthmatic preschool children had FeNO < 20 ppb. The oral contribution to FeNO was similar in asthmatic and healthy youths. Multiple flow rates and modelling of alveolar NO were feasible in children aged 10-18 years. Alveolar NO correlated to asthma characteristics, though not when axial diffusion correction was applied. FOT resistance measures were associated with asthma diagnosis, and small airway FOT measures were associated with asthma control, in adolescents. Conclusion: An adapted FeNO method is feasible from 4 years, and exhalation time is related to child height. Our findings emphasise the need to refine clinical cut-offs for FeNO in younger children. FOT variables discriminate between asthmatics and controls, much like spirometry. The information provided by FOT is additive to that from spirometry. Further studies of exhaled NO dynamics and FOT indices of small airways are warranted to evaluate new treatment options and possibly improve asthma control.

Comprendre de quelle façon les populations animales répondent aux conditions qui prévalent dans leur environnement revêt une grande importance. Les conditions climatiques et météorologiques sont une source importante de variabilité dans l'environnement et celles-ci ont des répercussions sur les espèces sauvages, en affectant leur physiologie, leur comportement et leurs ressources. Les ongulés alpins et nordiques font face à une succession annuelle de conditions environnementales favorables et défavorables, entraînant chez ceux-ci d'importants changements de masse saisonniers. Chez ces grands herbivores, la masse est importante puisqu'elle est positivement corrélée à la survie et à la reproduction. C'est pourquoi il est essentiel d'investiguer les paramètres affectant les changements de masse saisonniers. L'objectif principal de ma maîtrise était donc d'identifier et de mieux comprendre l'effet des conditions climatiques et météorologiques sur les changements de masse estivaux et hivernaux d'un ongulé alpin: le mouflon d'Amérique (Ovis canadensis). Pour atteindre cet objectif, j'ai utilisé les données du suivi à long terme de la population de mouflons de Ram Mountain, Alberta. Les mesures de masse répétées prises lors des captures permettent d'estimer la masse printanière et automnale des individus, ainsi que leur gain de masse estival et leur changement de masse hivernal. En affectant les coûts énergétiques de la thermorégulation et des déplacements et en influençant la végétation, les conditions climatiques et météorologiques peuvent avoir d'importantes conséquences sur les changements de masse des ongulés alpins. La température, les précipitations et un indice de climat global (le «Pacific Decadal Oscillation»; PDO) ont donc été utilisés afin de caractériser les conditions environnementales et d'investiguer les effets de ces variables sur les changements de masse saisonniers des individus de différentes classes d'âge et de sexe. Des températures froides au printemps ont engendré de plus grands gains de masse estivaux. Des printemps froids peuvent ralentir la maturation des plantes, engendrant une plus grande période où il est possible de s'alimenter de jeunes plantes nutritives, ce qui explique probablement cet effet positif des printemps froids. Cet effet doit toutefois être nuancé puisque les changements de masse hivernaux étaient également influencés par la température printanière, avec des printemps chauds menant à de plus faibles pertes de masse. Il semble que cet effet était dû à une apparition hâtive de la végétation, menant à une prise de masse des mouflons avant qu'ils ne soient capturés au printemps. Cela suggère qu'en affectant la disponibilité et la qualité de la végétation, les conditions printanières ont des répercussions à la fois sur le gain de masse estival, mais également sur les changements de masse hivernaux des mouflons. Le PDO au printemps a un effet positif important sur le gain de masse des adultes mâles lorsque la densité est faible. Des températures chaudes à l'automne engendrent de plus grands gains de masse pendant l'hiver chez les agneaux mâles (la plupart des agneaux gagnent de la masse l'hiver), potentiellement en augmentant la période possible de prise de masse pour ces jeunes individus. Les femelles de deux ans et les mâles adultes ont perdu plus de masse lors d'hivers avec beaucoup de précipitations et des températures froides, respectivement. Finalement, ce projet de recherche a permis d'identifier les variables climatiques et météorologiques clés affectant les changements de masse saisonniers d'un ongulé alpin. Cette étude a également mis en évidence des effets du PDO sur les changements de masse saisonniers, soulignant que de tels indices peuvent s'avérer utiles afin de les mettre en lien avec la variation phénotypique chez les espèces sauvages, et ce sans qu'il n'y ait nécessairement de fortes corrélations entre ces indices et les variables météorologiques locales.

Tidally-induced head fluctuation is a natural phenomenon in coastal regions. The discharge of groundwater through sediments will occur anywhere that the aquifer is hydraulically connected to a surface water body and the time averaged tidally-influenced water level in the aquifer is higher than sea level, and almost all coastal regions are subject to such flow. With the development of coastal areas, the discharge of groundwater contaminants into tidally affected coastal water bodies has become a significant problem. Biota that live in the benthic region are known to be sensitive to the concentration of discharging anthropogenic chemical compounds. Thus the contaminant concentration entering the benthos is of very significant practical importance and its study is the focus of this dissertation. An investigation of the effect of tides on the concentration of groundwater contaminants discharging to a surface water body is studied using a one-dimensional homogeneous sand column. Results of the experiment are confirmed using a three-dimensional heterogeneous groundwater tank model. A constant water level is imposed upgradient, and the downgradient water level is controlled by a wave generator that controls the hydraulic head to mimic a 12 hour tidal fluctuation. The experimental results demonstrate that the tidal fluctuations in the downgradient reservoir result in a decrease in average contaminant concentration at the point of groundwater discharge to the surface-water body. The further upstream the well is located, the smaller the amplitude of the concentration oscillation. In addition, upstream migration of concentration oscillations is observed in spite of a net downgradient flow. Fourier analysis suggests that the dominant frequency of the peaks of pressure and chemical data at different locations along the length of the column is identically two cycles per day and that the amplitudes of the concentration oscillations increase with time at measurement locations at the upstream responding probes. As the classical groundwater flow and transport model cannot reproduce the phenomena we observed, an innovative multi-mobility model, is proposed with one highly mobile liquid phase, one less mobile liquid phase and a solid phase. Averaging theory is applied to develop the mass conservation equation from the microscale to the macroscale and facilitate the reduction of dimensionality to obtain one-dimensional governing equations with closure relations. A new finite volume method is utilized to solve the resulting equations. The simulation confirms the existence of the enhanced tidally-induced mixing process.

The forced Oscillation Technique (FOT) can be used to measure lung impedance continuously during breathing. However, spectral overlap between the breathing waveform and the applied flow oscillation can be problematic if the frequency content of spontaneous breathing is unknown. This problem motivated us to develop a modification to the FOT system called the Tracked Breathing Trainer. The modification uses biofeedback to constrain subjects to breathe at a single predetermined frequency. This thesis investigates the engineering and physiological aspects of the modification we made. We studied 8 adult non-asthmatic and 8 adult asthmatic subjects. Three 16 s perturbatory flow oscillation signals ranging from 1-40 Hz were used on the subjects. Each subject received three trials per perturbation for both spontaneous and tracked breathing. We then fitted a resistance-elastance-inertance model of the lung to each data set. For non-asthmatic subjects, the average resistance (R) and elastance (E) values for the first spontaneous breathing trial were 2.5±0.15 cmH2O.s.ml-1 and 18.1±3.55 cmH2O.ml-1, and for the third spontaneous breathing trial were 2.4±0.12 cmH2O.s.ml-1 and 21.8±4 cmH2O.ml-1. R and E for the first tracked breathing trial were 2.3±0.21 cmH2O.s.ml-1 and 33.6±7.4 cmH2O.ml-1, and for the third tracked breathing trial were 2.4±0.14 cmH2O.s.ml-1 and 25.75±4.3 cmH2O.ml-1, respectively. For asthmatic subjects, the average R and E values for the first spontaneous breathing trial were 3.32±0.68 cmH2O.s.ml-1 and 39.13±9.8 cmH2O.ml-1, and for the third spontaneous breathing trial were 3.12±0.15 cmH2O.s.ml-1 and 39.91±6.2 cmH2O.ml-1. R and E for the first tracked breathing trial were 2.86±0.15 cmH2O.s.ml-1 and 32.47±4.1 cmH2O.ml-1, and for the third tracked breathing trial were 2.86±0.21 cmH2O.s.ml-1 and 33.89±10 cmH2O.ml-1, respectively. These results show that R was consistently lower during tracked breathing than spontaneous breathing in both non-asthmatic and asthmatic subjects. However, an increase in E was observed during tracked breathing. We suspect this effect may have resulted from dynamic hyperinflation. These results also show that R and E are reproducible with both spontaneous and tracked breathing, and that R and E were not noticeably different between both breathing maneuvers. We conclude that using biofeedback to control the breathing pattern during application of the FOT in normal subjects does not significantly affect impedance measurements, and thus may be useful for avoiding spectral overlap between FOT perturbations and the breathing pattern.

This study aims for knowledge about the most important climate features that affect the temperature and precipitation in the continental area of Central America. Systems such as The Caribbean Low Level Jet (CLLJ), The Intertropical Convergence Zone (ITCZ) and The Western Hemisphere Warm Pool (WHWP) components are major contributors to regional climate that strongly interact with the topographical features dividing the Pacific and Caribbean slopes of Central America. Daily data within a 35 year long (1981-2015) time-series of precipitation and temperature for 9 different meteorological stations along both slopes have been investigated to identify their relationship with El Niño Southern Oscillation (ENSO) phases. Missing data were filled in using rellenaf, a routine function developed at the Center for Geophysical Research of the University of Costa Rica. The function estimates data values with principal components and autoregressive methods. Data show that the Pacific slope is mainly characterized by a remarkable contrast between the dry season and the rainy season. The seasonal variations in precipitation are less important for the Caribbean slope. The annual cycle of temperature (for all of the stations) has small differences in amplitude and is rather stable throughout the year, except at the northernmost stations, Belize and Puerto Barrios, where relatively low temperatures dominate the winter months due to cold air intrusions. The low frequency atmospheric mode ENSO, impacts the regional climate and interacts with the earlier mentioned CLLJ, ITCZ and WHWP. Strong ENSO episodes of El Niño and La Niña were compared with anomalies in temperature, precipitation and winds at 925 hPa (mainly focusing on CLLJ). A contribution of negative (positive) anomalies in precipitation was observed during El Niño (La Niña) events for the Pacific slope. This relationship was not present for the Caribbean slope. No connection between the temperature and ENSO could be revealed. It was also shown that CLLJ is stronger (weaker) in February for La Niña (El Niño) and stronger (weaker) in July for El Niño (La Niña) events. / I syftet att utöka individuell kunskap om de viktigaste klimatsystemen som påverkar temperatur och nederbörd över den tropiska kontinenten Centralamerika, gjordes en studie. Komponenter såsom den karibiska lågaltituds-jeten (CLLJ The Caribbean Low Level Jet), den intertropiska konvergenszonen (ITCZ The Intertropical Convergence Zone) och västra halvklotets varmvattenspool (WHWP The Western Hemisphere Warm Pool) är huvudsakliga system som påverkar det regionala klimatet och dessa interagerar med topografin. I sin tur delar den upp Centralamerika i Stilla havssidan samt Karibiska sidan, två skiljda regioner ur ett meteorologiskt perspektiv. Dygnsdata, för temperatur och nederbörd inom en tidsperiod av 35 år (1981-2015) för 9 olika meteorologiska stationer, har undersökts för att identifiera mönster kopplat till den södra El Niño-oscillationen (ENSO The El Niño Southern Oscillation). Avsaknad data beräknades med rutinfunktionen rellenaf, som har utvecklats av universitetet i Costa Rica - Centret för geofysisk forskning. Funktionen estimerar datavärden utifrån principiella komponenter -och autoregressiv metod. Från den kompletta datan kunde det identifieras att Stilla havssidan är huvudsakligen kännetecknat av en torrperiod och en regnperiod, medan säsongsvariationerna i nederbörd för Karibiska sidan är mindre. Den årliga temperaturcykeln för hela regionen erhåller små skillnader i amplitud, med andra ord är temperaturen mer eller mindre konstant genom årets gång. Med undantag för de mer nordliga stationerna Belize och Puerto Barrios där lägre temperaturer förekommer under norra halvklotets vintermånader som är orsakat av kallfronter. ENSO är ett lågfrekvent atmosfäriskt system som har påverkan på det regionala klimatet genom att interagera med de tidigare nämna CLLJ, ITCZ and WHWP. De starka faserna El Niño och La Niña observerades och jämfördes med anomalier för temperatur, nederbörd och vindfält på 925 hPa nivå (huvudsakligen fokus på CLLJ). En majoritet av negativa (positiva) anomalier för nederbörd kunde observeras under El Niño (La Niña) fenomen för Stilla havssidan. Dock fanns inte denna relation för den Karibiska sidan. Det fanns heller ingen koppling mellan temperatur och ENSO. Det kunde även ses att CLLJ är starkare (svagare) i februari för la niña (el niño) och starkare (svagare) i juli för el niño (la niña).

Dans ces travaux de thèse, nous avons étudié les propriétés dynamiques et spectrales d’une diode laser puissante à 980 nm qui est soumise à un retour optique provenant d’un réseau de Bragg fibré (FBG). Dans cette configuration, le FBG est un élément clé de la thèse d’une part il permet de former une cavité externe par réflexion comme un miroir et d’autre part il est un filtre qui fournit un retour optique sélectif en fréquence (FOF : Filtered Optical Feedback) aux alentours de 980 nm. Nous nous sommes intéressé à étudier cette configuration FOF dans le cadre d’un projet de collaboration entre la société 3S Photonics Group et le Laboratoire de Physique des Lasers. Il s’agit plus particulièrement d’étudier expérimentalement les séries temporelles par un oscilloscope, les spectres RF par un analyseur de spectre RF et les spectres optiques par un analyseur de spectre optique et par un interféromètre Fabry-Perot, afin d’observer, identifier et comprendre ses comportements dynamiques, notamment fluctuations basses fréquences (LFF). Ce système laser FOF est très peu étudié et ces travaux de thèse permettront de nouvelles connaissances techniques ou scientifiques dans un domaine d’application relativement récent, notamment pour l’application dans les systèmes EDFA (Erbium Doped Fiber Amplifier). / In this thesis, we have studied spectrums and the dynamics properties of a high-powerlaser diode emitting at 980 subject to optical feedback via a fibre Bragg grating (FBG). In such a configuration, FBG is a key element of this work because it establishes an ex-ternal cavity with a reflection like a mirror on one hand and it is a filter which provides frequency selective optical feedback (FOF : Filtered Optical Feedback) at around 980 nm on the other hand. We are interested in investigating this FOF configuration for a project in a collaboration between 3S Photonics Group and the Laboratoire de Physique des Lasers.In order to observe, identify and understand its dynamical behaviours, especially low frequency fluctuations (LFF), the experimental studies have been undertaken particularly with time series from an oscilloscope, RF spectra from an RF spectrum analyser and optical spectra from an optical spectrum analyser and Fabry-Perot interferometer. Onlyfew studies have been done with this FOF laser system and our thesis work may allow new technical and scientific understanding for recent application, particularly application to Erbium-doped fibre amplifier.

As reações químicas genericamente referidas como reações de Belousov-Zhabotinsky (BZ) têm sido bastante utilizadas como paradigmas de complexidade em sistemas químicos homogêneos. Apesar dos avanços consideráveis realizados no estudo de tais sistemas, aspectos como o papel do fluxo de reagentes e da temperatura na dinâmica oscilatória ainda são pouco entendidos. O presente trabalho consiste na investigação experimental do efeito destes dois parâmetros em duas variantes da reação de BZ. Após alguns testes iniciais com o sistema bromato/hipofosfito-acetona/manganês-ferroína, a maioria dos experimentos foi feita com o sistema bromato/ácido oxálico-acetona/cério. A evolução temporal do sistema foi estudada a diferentes temperaturas e em condições de batelada e de fluxo por meio do monitoramento simultâneo do potencial de um eletrodo de platina e espectrofotometricamente na região do UV-vis. A discussão foi baseada na energia de ativação em regime oscilatório, Eω. Para o sistema com dois catalisadores não foram observadas oscilações nas condições de fluxo. Para o sistema com cério, em batelada, com Ce4+ é observado que Eω aumenta conforme o sistema evolui para o estado de equilíbrio termodinâmico. Com Ce3+, em batelada, Eω manteve-se praticamente constante e em fluxo, o valor de Eω foi menor do que o valor observado para o sistema em batelada. / The chemical reactions usually referred to as the Belousov-Zhabotinsky (BZ) reactions have been extensively employed as paradigms of complexity in homogeneous chemical systems. In spite of the considerable advance in the study of such systems, aspects such as the role played by the flux of reactants and temperature on the oscillatory dynamics are still poorly understood. The present work consists of the experimental investigation of the effect of these two parameters on two variants of the BZ reaction. After some initial tests with the bromate/hipophosphite-acetone/manganese-ferroin, most of the experiments were carried with the bromate/oxalic acid-acetone/cerium system. The time-evolution of the system was followed at different temperatures and under batch and flow conditions by means of potentiometric and spectrophotometric (UV-vis region) approaches. The discussion was based on the activation energy under oscillatory regime, Eω. For the two-catalyst system, no oscillations were observed under flow conditions. For the cerium-catalyzed system operated in batch, when Ce4+ is used, it is observed that Eω increases as the system evolves to the thermodynamic equilibrium. With Ce3+, the Eω under batch conditions remained virtually constant and in flow, the value of Eω was lower than the value observed for the batch system.

by Yeung Wai Lung. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2002. / Includes bibliographical references (leaves 120-122). / Text in English; abstracts in English and Chinese. / by Yeung Wai Lung. / Abstract --- p.i / Abstract (Chinese version) --- p.ii / Acknowledgements --- p.iii / Contents --- p.iv / List of figures --- p.vii / List of tables --- p.xi / Chapter 1 --- Introduction --- p.1 / Chapter 2 --- The El Nino ´ؤ Southern Oscillation Phenomenon --- p.3 / Chapter 2.1 --- Introduction to El Nino - Southern Oscillation --- p.3 / Chapter 2.2 --- The mean conditions of the Tropical Ocean --- p.4 / Chapter 2.3 --- Life Cycle of ENSO --- p.8 / Chapter 2.4 --- Understanding ENSO --- p.12 / Chapter 3 --- ENSO prediction schemes --- p.18 / Chapter 3.1 --- Introduction --- p.18 / Chapter 3.2 --- Statistical prediction models --- p.19 / Chapter 3.2.1 --- Introduction --- p.19 / Chapter 3.2.2 --- Atmospheric models --- p.19 / Chapter 3.2.3 --- Oceanic models --- p.22 / Chapter 3.3 --- Coupled ocean-atmosphere models --- p.24 / Chapter 3.3.1 --- Introduction --- p.24 / Chapter 3.3.2 --- Intermediate coupled models --- p.25 / Chapter 3.3.3 --- Hybrid coupled models --- p.28 / Chapter 3.3.4 --- Coupled general circulation models --- p.30 / Chapter 3.4 --- Skill sensitivities --- p.36 / Chapter 3.4.1 --- Introduction --- p.36 / Chapter 3.4.2 --- Dependence of skill on season --- p.36 / Chapter 3.4.3 --- Dependence of skill on decade --- p.37 / Chapter 3.4.4 --- Dependence of skill on the Phase of the ENSO cycle --- p.38 / Chapter 4 --- The ENSO model --- p.40 / Chapter 4.1 --- Introduction --- p.40 / Chapter 4.2 --- Models formalism --- p.40 / Chapter 4.2.1 --- Oceanic model --- p.40 / Chapter 4.2.2 --- Atmospheric model --- p.43 / Chapter 4.2.3 --- Coupling of atmospheric and oceanic models --- p.44 / Chapter 4.3 --- Numerical implementation --- p.45 / Chapter 4.3.1 --- Oceanic model --- p.45 / Chapter 4.3.2 --- Atmospheric model --- p.49 / Chapter 4.3.3 --- Averaging and interpolation during coupling --- p.52 / Chapter 4.4 --- Standard response of the model --- p.54 / Chapter 4.5 --- Limitation of the model --- p.57 / Chapter 5 --- Behavior of the ENSO model --- p.59 / Chapter 5.1 --- Introduction --- p.59 / Chapter 5.2 --- Numerical results of the model --- p.60 / Chapter 5.3 --- Effects of the parameters --- p.62 / Chapter 5.3.1 --- Introduction --- p.62 / Chapter 5.3.2 --- Coupling constant parameters --- p.62 / Chapter 5.3.3 --- Rayleigh friction --- p.66 / Chapter 5.3.4 --- The oceanic Kelvin wave speed --- p.69 / Chapter 5.3.5 --- The ocean basin length --- p.69 / Chapter 5.3.6 --- Reflections at the western boundary --- p.74 / Chapter 5.4 --- Modification of the model background state --- p.76 / Chapter 5.4.1 --- Introduction --- p.76 / Chapter 5.4.2 --- The results of the modified model --- p.77 / Chapter 5.4.3 --- Sensitivity of the western boundary of the modified model --- p.81 / Chapter 5.4.4 --- Parameters sensitivities of the modified model --- p.83 / Chapter 5.5 --- Conclusion and discussion --- p.87 / Appendix A --- p.91 / Appendix B --- p.112 / Bibliography --- p.120

Cette étude a été divisée en 2 parties principales. Dans la première partie, nous examinons la relation entre l'activité des sources neuronales et les HFOs observés sur les électrodes intracérébrales. La deuxième partie traite de l'étude des conditions d'observabilité des HFO sur les électrodes du cuir chevelu. Les simulations ont montré que le modèle de champ neuronal proposé est capable de générer des HFOs montrant une forte ressemblance avec les signaux réels dans les deux cas EEG (cuir chevelu) et SEEG (intracérébral). De plus, nous avons pu relier les mécanismes physiopathologiques (GABA dépolarisant, inhibition directe, activité désynchronisée des populations neuronales) aux différentes caractéristiques morphologiques et spectrales des HFOs intracérébrales. Une hypothèse unifiée pour la production des HFOs et des pointes intercritiques est également formulée. Enfin, nous avons réussi à établir les conditions nécessaires sur l'activité temporelle et l'organisation spatiale des sources neuronales pour observer des HFOs sur les électrodes intracérébrales.En ce qui concerne la deuxième partie, la baisse inexpliquée de fréquence dans les HFOs collectées sur les électrodes du cuir chevelu a été abordée. Nous avons constaté que les mécanismes «non oscillatoires» de la génération de HFOs sont à l'origine de la faible fréquence (<200Hz) des HFOs du cuir chevelu et que le rapport signal / bruit (SNR) influe fortement sur la fréquence des oscillations. De plus, nous avons étudié la topographie des HFOs sur les électrodes du cuir chevelu et analysé comment cette topographie est affectée par différents paramètres (étendue spatiale épileptique, SNR, géométrie 3D). Enfin, nous avons montré que les HFOs du cuir chevelu peuvent être utilisés efficacement pour identifier la zone épileptique lorsque le rapport signal sur bruit des signaux enregistrés est suffisamment élevé. Une perspective de ce travail est l'identification non-invasive de la zone épileptique sans la nécessité d'enregistrements intracérébraux pré-chirurgicaux.Pour les deux études (HFO observés sur les électrodes intracérébrales et du cuir chevelu), un logiciel original et convivial a été développé. Ce logiciel a fortement facilité la simulation des signaux dans l'environnement cerveau/électrode virtuel, signaux obtenus en résolvant le problème direct de l’EEG (projection de la contribution électrique des sources neuronales sur les capteurs). / This study was divided into 2 main parts. In the first part, we address the relationship between the activity of neuronal sources and the HFOs observed on intracerebral electrodes. The second part deals with the investigation of observability conditions of HFOs on scalp electrodes. Simulations showed that the proposed neural field model is capable of generating HFOs showing strong resemblance with real signals in both cases EEG (scalp) and SEEG (intracerebral). Moreover, we were able to relate the pathophysiological mechanisms (depolarizing GABA, feedforward inhibition, desynchronized activity of neuronal populations) to different morphological and spectral features of intracerebral HFOs. A unified hypothesis for generation of HFOs and interictal spikes is also formulated. Finally, we managed to establish the necessary conditions about the temporal activity and the spatial organization of neuronal sources and about for HFOs to be observed on intracerebral electrodes. Regarding the second part, the unexplained drop in frequency in the collected HFOs on scalp electrodes was addressed. We found that the “non-oscillatory” mechanisms of the HFO generation is behind the low frequency (<200Hz) in scalp HFOs and that signal to noise ratio (SNR) heavily impacts the frequency of the oscillations. Moreover, we studied the topography of HFOS on scalp electrodes and analyzed how this topography is affected by different parameters (epileptic spatial extent, SNR, 3D geometry). Finally we showed that scalp HFOs can be effectively used to identify the epileptic zone when the SNR of the recorded signals is sufficiently high. A perspective to this work is the non-invasive identification of epileptic zone without the need for presurgical intracerebral recordings. For the purpose of both studies (HFOs observed on intracerebral & scalp electrodes) an original and user-friendly software package was developed. This software strongly facilitated the simulation of signals in the virtual brain/electrode environment obtained by solving the (S)EEG forward problem (projection of the electric contribution of neuronal sources onto electrode contacts).

A oscilação em malhas de controle é um problema frequente na indústria, atingindo cerca de 30% das malhas, entre as causas, o agarramento em válvulas de controle possui maior incidência. O agarramento é a resistência ao movimento da haste da válvula devido à presença de atrito estático, a combinação desse fator com a utilização de controladores com ação integral causa o ciclo limite no processo, onde a oscilação é mantida até que alguma ação seja tomada. A literatura apresenta diversos métodos para a detecção do agarramento, apesar disso, não existe método aplicável a qualquer tipo de processo que apresente resultado preciso, um dos principais problemas para a aplicação das técnicas é a presença de referência variável no sinal a ser analisado. A referência variável é uma característica comum dentro de processos industriais, principalmente para processos controlados por malha cascata ou que apresentam distúrbios externos. Para a identificação nesses casos, duas alternativas podem ser seguidas: criação de nova metodologia para a identificação do agarramento para sinais com referência variável ou a adaptação das técnicas existentes de modo que essas sejam aplicáveis a esse tipo de sinal, neste trabalho, as duas alternativas foram consideradas. Primeiramente, duas novas técnicas baseadas na forma do sinal foram criadas, a primeira diferencia o sinal pela inclinação dos picos e a segunda pela distribuição dos dados. Posteriormente, foi considerada a adaptação de quatro métodos de detecção já consolidados pela literatura e por suas aplicações industriais. A adaptação dos métodos é basicamente feita através do pré-processamento dos sinais de modo que esses sejam corretamente tratados antes da aplicação das técnicas de detecção. As duas alternativas foram aplicadas a dados simulados e industriais, comprovando a eficiente para a detecção em sinais com referência variável. / Oscillation in control loops is a frequent problem in industrial processes, reaching about 30% of the control loops, among the causes, stiction in control valves have the higher incidence. Stiction is the resistance to movement in the valve stem due to the presence of static friction, the combination of this factor with the use of controller with integral action induces the limit cycle, where the oscillation is sustained until some control action is taken. The literature presents several methods for stiction detecting. However, there is no universal method applicable for all process that produces accurate results. The main problems for the application of the techniques are the presence of variable reference in the signal to be analyzed. The reference variable is a common feature in industrial processes, especially for processes controlled by cascade loop or submitted to external disturbances. For stiction identification in these cases, two choices can be followed: a creation of a new methodology for the identification of stiction for signals with variable reference or the modification of existing techniques so that they could be applied to this type of signal. In this work, the two alternatives were considered. First, two new techniques based on the signal form were created, the first differentiates the signal by the slope of the peaks and the second by data segmentation. Later the adaptation of four detection methods already established in the literature and by its industry applications was considered. The adaptation is done by preprocessing the signals so that they are properly treated before application. The two alternatives were applied to simulated and industrial data, proving to be effective for the stiction detection of signals with variable references.