Dissertations / Theses on the topic 'Relaxed control'
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Zhao, Yanbin. "Relaxed stability analysis of fuzzy-model-based control systems." Thesis, King's College London (University of London), 2018. https://kclpure.kcl.ac.uk/portal/en/theses/relaxed-stability-analysis-of-fuzzymodelbased-control-systems(df7ec615-6b23-4344-844d-00300a43f975).html.
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This thesis presents and extrapolates on the research works concerning the stability analysis of fuzzy-model-based (FMB) control systems. In this study, two types of FMB control systems are considered: 1) Takagi-Sugeno (T-S) FMB control systems; and 2) polynomial fuzzy-model-based (PFMB) control systems. The control scheme illustrated in this thesis has great design flexibility because it allows the number and/or shape of membership functions of fuzzy controllers to be designed independently from the fuzzy models. However, in wake of the imperfectly matched membership functions, the stability conditions of the FMB control systems are typically very conservative given the fact that they are con-gruent with traditional stability analysis methods. In this thesis, based on Lya-punov stability theory, membership-function-dependent (MFD) stability analysis methods are proposed to relax the stability conditions. Firstly, piecewise mem-bership functions (PMFs) are utilised as approximate membership functions to carry out a relaxed stability analysis of T-S FMB control system. Subsequently, PMF-based stability analysis is improved with the consideration of membership function boundary information. Based on the PMF method, we propose a lower-upper-PFM-based stability analysis method. Relaxed stability conditions are obtained in the form of linear matrix inequalities (LMIs) in consideration of the approximation accuracy of the membership function. For the purpose of stability analysis of PFMB control system, the other MFD method proposed is to extract the regional membership function information via operating domain partition. Two types of membership information are consid-ered in each sub-domain: 1) the numerical relationship between all membership function overlap terms; and 2) the bounds of every single membership function overlap term. Thereafter, relaxed sum of squares (SOS)-based stability conditions are derived. In conjunction with these proposed MFD methods, sub-domain fuzzy controllers are utilised to enhance the capability of feedback compensation. In this thesis, all the LMI/SOS-based stability conditions obtained can be solved nu-merically using existing computational tools. Furthermore, simulation examples are provided to illustrate the validity and applicability of the proposed methods.
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Ariño, Latorre Carlos Vicente. "Relaxed LMI conditions for control of nonlinear Takagi-Sugeno models." Doctoral thesis, Universitat Politècnica de València, 2010. http://hdl.handle.net/10251/8301.
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Los problemas de optimización de desigualdades matriciales lineales en control borroso se han convertido en la herramienta más utilizada en dicha área desde los años 90. Muchos sistemas no lineales pueden ser modelados como
sistemas borrosos de modo que el control borroso puede considerarse como una técnica de control no lineal. Aunque se han obtenido muchos y buenos resultados, quedan algunas fuentes de conservadurismo cuando se comparan con
otros enfoques de control no lineal. Esta tesis discute dichas cuestiones de conservadurismo y plantea nuevos enfoques para resolverlas.
La principal ventaja de la formulación mediante desigualdades matriciales lineales es la posibilidad de asegurar estabilidad y prestaciones de un sistema no lineal modelado como un sistema borroso Takagi-Sugeno. Estos
modelos están formados por un conjunto de modelos lineales eligiendo el sistema a aplicar mediante el uso de unas reglas borrosas. Estas reglas se traducen en funciones de interpolación o de pertenecía que nos indican el
grado de validez de un modelo lineal respecto del resto. El mayor problema que presentan estas técnicas basadas en desigualdades matriciales lineales es que las funciones de pertenencia no están incluidas en las condiciones de
estabilidad del sistema, lo que significa que se prueba la estabilidad y prestaciones para cualquier forma de interpolación entre los diferentes modelos lineales. Esto genera una fuente de conservadurismo que sería conveniente limitar.
En la tesis doctoral se presentan varias metodologías capaces de trasladar la información de las funciones de pertenencia del sistema al problema basado en desigualdades matriciales lineales de estabilidad y prestaciones. Las dos principales aportaciones propuestas se basan, respectivamente, en introducir una serie de matrices de relajación que permitan incorporar esta información y en aprovechar la descripción de una amplia clase de sistemas borrosos en
productos tensoriales de...Ariño Latorre, CV. (2008). Relaxed LMI conditions for control of nonlinear Takagi-Sugeno models [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/8301
Palancia
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Liu, Chuang. "Relaxed stability analysis for fuzzy-model-based observer-control systems." Thesis, King's College London (University of London), 2016. https://kclpure.kcl.ac.uk/portal/en/theses/relaxed-stability-analysis-for-fuzzymodelbased-observercontrol-systems(082673fa-9a83-4cda-8622-9358ed8d7118).html.
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Fuzzy-model-based (FMB) control scheme is an efficient approach to conduct stability analysis for nonlinear systems. Both Takagi-Sugeno (T-S) FMB and polynomial fuzzy-model-based (PFMB) control systems have been widely investigated. In this thesis, the stability analysis of FMB control systems is conducted via Lyapunov stability theory. The main contribution of the thesis is improving the applicability of T-S FMB and PFMB control strategies by relaxing stability conditions and designing fuzzy observer-controller, which is presented in the following three parts: 1) The stability conditions of FMB control systems are relaxed such that the FMB control strategy can be applied to a wider range of nonlinear systems. For T-S FMB control systems, higher order derivatives of Lyapunov function (HODLF) are employed, which generalizes the commonly used first order derivative. For PFMB control systems, Taylor series membership functions (TSMF) are brought into stability conditions such that the relation between membership grades and system states is expressed. 2) Two types of T-S fuzzy observer-controller are designed such that the T-S FMB control strategy can be applied to systems with unmeasurable states. For the first type, the T-S fuzzy observer with unmeasurable premise variables is designed to estimate the system states and then the estimated states are employed for state-feedback control of nonlinear systems. Convex stability conditions are obtained through matrix decoupling technique. For the second type, the T-S fuzzy functional observer is designed to directly estimate the control input instead of the system states, which can reduce the order of the observer. A new form of fuzzy functional observer is proposed to facilitate the stability analysis such that the observer gains can be numerically obtained and the stability can be guaranteed simultaneously. 3) The polynomial fuzzy observer-controller with unmeasurable premise variables is designed for systems with unmeasurable states. Although the consideration of the polynomial fuzzy model and unmeasurable premise variables enhances the applicability of the FMB control strategy, it leads to non-convex stability conditions. Therefore, two methods are applied to derive convex stability conditions: refined completing square approach and matrix decoupling technique. Additionally, the designed polynomial fuzzy observer-controller is extended for systems where only sampled-output measurements are available. Furthermore, the membership functions of the designed polynomial observer-controller are optimized by the improved gradient descent method. Simulation examples are provided to demonstrate and verify the theoretical analysis.
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Meneses, Cortés Matías Ignacio. "Desclasificación basada en tipos en DART: Implementación y elaboración de herramientas de inferencia." Tesis, Universidad de Chile, 2018. http://repositorio.uchile.cl/handle/2250/168368.
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Ingeniero Civil en ComputaciónLa protección de la confidencialidad de la información manipulada por los programas computacionales es abordada a nivel del código fuente con distintas técnicas. Una de ellas es tipado de seguridad para el control de flujo, que controla el nivel de seguridad donde fluye la información agregando anotaciones a las variables tipadas. La propiedad de seguridad fundamental de control de flujo es conocida como no-interferencia (noninterference), que establece que un observador público no puede obtener conocimiento desde datos confidenciales. A pesar de ser una propiedad muy atractiva, los sistemas reales la vulneran fácilmente, y necesitan mecanismos para desclasificar selectivamente alguna información. En esta dirección, Cruz et al. proponen una forma de desclasificación basada en tipos (type-based declassification), en donde se utilizan las relaciones de subtipos del lenguaje para expresar las políticas de desclasificación de los datos que maneja el programa, en una forma simple y expresiva. A pesar de que el fundamento teórico de la desclasificación basada en tipos está bien descrito, carece de una implementación que permita comprobar la utilidad práctica de la propuesta. En este trabajo, se implementa el análisis de la desclasificación basada en tipos para un subconjunto del lenguaje Dart, un lenguaje de programación de propósito general orientado a objetos desarrollado por Google. Además, se implementó un sistema de inferencia de políticas de desclasificación y una extensión para ambientes de desarrollo, con el objetivo de facilitar el trabajo al programador y mejorar su experiencia.
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Ruehle, Matthew A. "The Effect of Nicotine on the Default Mode Network, Executive Control Network, and Salience Network During Relaxed and Stressed Resting States As a Function of Trait Negative Affect." OpenSIUC, 2017. https://opensiuc.lib.siu.edu/theses/2162.
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Researchers have studied nicotine’s ability to attenuate stress and negative affect for decades, but there has been limited research into the cortical regions most responsible for these effects. Recent paradigms have emerged that define large-scale neural networks that operate in conjunction to elicit complex effects: the Default Mode Network (DMN), the Executive Control Network (ECN), and the Salience Network (SN). The current study utilized archival topographic (surface) EEG recordings to analyze the tomographic (3-dimensional) cortical differences in three major large-scale neural networks during relaxing and task-induced anticipatory stress resting states while nicotine-satiated and nicotine-deprived, and as a function of trait negative affect (NA). Various interaction and main effects of nicotine use, stress, and NA occurred in the connectivity between regions of interest (ROIs) of all three networks. Total current source density (CSD) analyses demonstrated an interaction between smoking and stress, such that the effects of smoking and stress were highest during the combination of deprivation and stress, and lowest when individuals were in nicotine satiated and in the low stress condition. A whole-brain exploratory analysis also identified a significant interaction between smoking and NA in the postcentral gyrus.
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Mezerdi, Mohamed Amine. "Equations différentielles stochastiques de type McKean-Vlasov et leur contrôle optimal." Electronic Thesis or Diss., Toulon, 2020. http://www.theses.fr/2020TOUL0014.
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Nous considérons les équations différentielles stochastiques (EDS) de Mc Kean-Vlasov, qui sont des EDS dont les coefficients de dérive et de diffusion dépendent non seulement de l'état du processus inconnu, mais également de sa loi de probabilité. Ces EDS, également appelées EDS à champ moyen, ont d'abord été étudiées en physique statistique et représentent en quelque sorte le comportement moyen d'un nombre infini de particules. Récemment, ce type d'équations a suscité un regain d'intérêt dans le contexte de la théorie des jeux à champ moyen. Cette théorie a été inventée par P.L. Lions et J.M. Lasry en 2006, pour résoudre le problème de l'existence d'un équilibre de Nash approximatif pour les jeux différentiels, avec un grand nombre de joueurs. Ces équations ont trouvé des applications dans divers domaines tels que la théorie des jeux, la finance mathématique, les réseaux de communication et la gestion des ressources pétrolières. Dans cette thèse, nous avons étudié les questions de stabilité par rapport aux données initiales, aux coefficients et aux processus directeurs des équations de McKean-Vlasov. Les propriétés génériques de ce type d'équations stochastiques, telles que l'existence et l'unicité, la stabilité par rapport aux paramètres, ont été examinées. En théorie du contrôle, notre attention s'est portée sur l'existence et l'approximation de contrôles relaxés pour les systèmes gouvernés par des EDS de Mc Kean-VlasovWe consider Mc Kean-Vlasov stochastic differential equations (SDEs), which are SDEs where the drift and diffusion coefficients depend not only on the state of the unknown process but also on its probability distribution. These SDEs called also mean- field SDEs were first studied in statistical physics and represent in some sense the average behavior of an infinite number of particles. Recently there has been a renewed interest for this kind of equations in the context of mean-field game theory. Since the pioneering papers by P.L. Lions and J.M. Lasry, mean-field games and mean-field control theory has raised a lot of interest, motivated by applications to various fields such as game theory, mathematical finance, communications networks and management of oil resources. In this thesis, we studied questions of stability with respect to initial data, coefficients and driving processes of Mc Kean-Vlasov equations. Generic properties for this type of SDEs, such as existence and uniqueness, stability with respect to parameters, have been investigated. In control theory, our attention were focused on existence, approximation of relaxed controls for controlled Mc Kean-Vlasov SDEs
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Yago, Llamas Daniel. "A new computational approach to topology optimization in solid mechanics problems." Doctoral thesis, Universitat Politècnica de Catalunya, 2022. http://hdl.handle.net/10803/673572.
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This doctoral thesis addresses topology optimization problems at a single scale. Based on this purpose, a new topology optimization approach is developed in order to improve existing and widespread techniques in the research community on the topic. The proposed technique presents several characteristics that overcome some of the well-known difficulties in topological optimization while maintaining a considerable degree of simplicity.
In the first place, the formulation of the topological optimization technique is presented, as well as its algorithm. The method is based on 4 fundamental features: (1) the use of a 1-0 characteristic function, as well as the precise identification of the material boundaries from a discrimination function (0-level-set function), (2) the definition of a topological derivative consistent with the ersatz method (used in the state problem), as an approximation to the exact topological derivative, (3) the inclusion of a Laplacian regularization with minimum size control of the different components, and (4) the formulation of an analytical optimality condition aiming at the optimal topology solution.
The approach is applied to different topology optimization problems, well-reported in the literature and used as numerical benchmarks (in structural and thermal problems), to examine their performance. In these fields, stiffness and conductivity maximization problems are considered for validation, respectively. In addition, different topological optimization problems of major engineering interest are tackled, including the design of compliant mechanisms within the structural field and thermal cloaking devices within the thermal field.
Finally, a comparison of the formulation with other existing topology optimization techniques is performed, including (1) SIMP, (2) ESO/BESO, and (3) Level-set with Hamilton-Jacobi as the updating equation. The analysis of the results provides a comparison in terms of the quality of the topology of each method, the computational cost of the optimal solutions, as well as the simplicity of implementation. The resulting study reveals the potential of the developed methodology in these specific comparison terms.
In an attempt to bring the method closer to other researchers and to promote its use, an educational version of the method (written in MATLAB) has been published in an online repository, together with documentation, facilitating its dissemination
and subsequent use in other applications of interest.El objetivo de esta tesis doctoral es abordar el problema de optimización topológica a una única escala. En base a este propósito, se desarrolla una nueva técnica de optimización capaz de competir con técnicas ya existentes y extendidas entre la comunidad investigadora sobre el tema. Esta técnica presenta características que superan algunas de las dificultades bien conocidas en optimización topológica manteniendo un buen grado de simplicidad. En primer lugar, se presenta la formulación de la técnica de optimización topológica, así como su algoritmia. El método se fundamenta en 4 aspectos básicos: (1) la utilización de una función característica 1-0, así como la definición precisa de las fronteras materiales a partir de una función de discriminación (isonivel 0 de la función level-set), (2) la definición de una derivada topológica coherente con el método ersatz (utilizado en la ecuación de estado), como aproximación a la derivada topológica exacta, (3) la inclusión de una regularización Laplaciana con control de tamaño mínimo de los diferentes componentes, y (4) la definición de una condición de optimalidad analítica para la determinación de la solución óptima de la topología. La metodología se aplica a diferentes problemas de optimización topológica bien detallados en la literatura y utilizados como ensayos numéricos para examinar su respuesta frente a problemas estructurales y térmicos. En estos campos, se incluyen problemas de maximización de la rigidez y de la conductividad, respectivamente. Además, se resuelven diferentes problemas de optimización topológica con gran interés ingenieril en los campos estructurales con el diseño de mecanismos y térmicos con el diseño de dispositivos de camuflaje térmicos. Finalmente, se realiza una comparación de la formulación con otras técnicas ya existentes, por ejemplo: (1) SIMP, (2) ESO/BESO, y (3) Level-set con Hamilton-Jacobi como ecuación de evolución. El análisis de los resultados permite comparar la calidad de la topología de cada método, el coste computacional de las soluciones óptimas, así como la simplicidad de implementación, demostrando el potencial de la metodología desarrollada principalmente en estos términos de comparación. Con la finalidad de acercar el método a otros investigadores y de promover su utilización, se ha publicado una versión educativa del mismo (en MATLAB) en un repositorio online, junto a documentación, permitiendo así la divulgación del mismo y la posible utilización en otras aplicaciones de interés.
Enginyeria mecànica, fluids i aeronàutica
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Abouhajar, Alaa Abdulwahab Abdulrahman. "Function theory related to H∞ control." Thesis, University of Newcastle Upon Tyne, 2012. http://hdl.handle.net/10443/1412.
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We define Γ(E), a subset of C³, related to the structured singular value μ of 2x2 matrices. μ is used to analyse performance and robustness of linear feedback systems in control engineering. We find a characterisation for the elements of Γ(E) and establish a necessary and sufficient condition for the existence of an analytic function from the unit disc into Γ(E) satisfying an arbitrary finite number of interpolation conditions. We prove a Schwarz Lemma for Γ(E) when one of the points in Γ(E) is (0,0,0), then we show that in this case, the Carathéodory and Kobayashi distances between the two points in Γ(E) coincide. We also give a characterisation of the interior, the topological boundary and the distinguished boundary of Γ(E), then we define Γ(E)-inner functions and show that if there exists an analytic function from the unit disc into Γ(E) that satisfies the interpolating conditions, then there is a rational Γ(E)-inner function that interpolates.
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Markdahl, Johan. "Rigid-Body Attitude Control and Related Topics." Doctoral thesis, KTH, Optimeringslära och systemteori, 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-175438.
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This dissertation explores aspects of control in rigid-body and robotic systems. The first and second paper analyze the attitude stabilization problem and its generalization to n-dimensional rigid bodies. The third and fourth paper are on cooperative control design for systems that evolve on the n-sphere and related topics such as rigid-body reduced attitude synchronization. The fifth, and final, paper proposes a hybrid systems approach to task-priority based control for mobile manipulation. he first and second paper concern the problem of attitude tracking by kinematic actuation for a class of almost globally asymptotically stabilizing feedback laws on SO(n). The closed-loop systems are solved exactly for the rotation matrices as functions of time. Exact solutions provide insight into both the transient and asymptotical behavior of a system. Applications of these results are found in model predictive control and in sampled systems. The second paper also solves the optimal control problem of geodesic reduced attitude stabilization subject to full attitude stabilization. The third and fourth paper concern three cooperative control problems on the n-sphere with applications to reduced attitude synchronization and formation control. The global behavior of a consensus protocol is studied both forwards and backwards in time. The forward time stability properties of all equilibria are characterized for a non-trivial class of graph topologies. The reverse time behavior in the case of cyclic graph topologies results in two types of formations depending on the parity of the number of agents. A third control protocol renders the centroid of agent states constant. The fifth, and final, paper proposes a hybrid control approach to task priority based planar mobile manipulation, i.e., control on the n-torus. The end-effector path following problem for a nonholonomic mobile manipulator is solved subject to constraints on the input norm, feasible joint configurations, and distance to singularities. The hybrid system is well-posed; there is no Zeno behavior or chattering. A continuous, time-independent feedback law is derived based on the hybrid control design.QC 20151015
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Fernandes, João Luís Gameiro. "Efeitos do suster-relaxar na cinemática tridimensional, função neuromuscular e sintomatologia álgica de um atleta de crossfit com dor lombar: um estudo de caso." Bachelor's thesis, [s.n.], 2016. http://hdl.handle.net/10284/5730.
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Projeto de Graduação apresentado à Universidade Fernando Pessoa como parte dos requisitos para obtenção do grau de Licenciado em FisioterapiaIntrodução: A lombalgia está associada a alterações da atividade muscular e da cinemática lombo-pélvica provocada, em parte, pela fraqueza da musculatura do core. O teste de Thomas é utilizado nas áreas clínica e desportiva para determinar o encurtamento do ilíopsoas e do reto femoral, músculos constituintes do core. O encurtamento destes músculos é um dos fatores de risco de lesão músculo-esquelética nos membros inferiores e de dor lombar. A técnica de suster-relaxar, aumenta a amplitude de movimento articular, normalizando o tónus muscular. Objetivo: Avaliar o efeito da técnica de suster-relaxar na cinemática tridimensional do teste de Thomas, na função neuromuscular e sintomatologia álgica de um atleta de crossfit com dor lombar à direita. Metodologia: Análise da cinemática tridimensional do teste de Thomas através do sistema de captura e análise de movimento 3D, Qualisys Oqus Camera Series, e força isocinética dos joelhos pela dinamometria isocinética, antes e após a aplicação técnica suster-relaxar num atleta de crossfit de 25 anos. Resultados: Após a análise dos dados obtidos, verificou-se um aumento da amplitude de extensão da anca, do peak torque e diminuição da sintomatologia álgica, no lado afetado do atleta, em resultado da aplicação da técnica de suster-relaxar. Conclusão: A técnica suster-relaxar aumenta a amplitude de movimento articular, e o peak torque e diminui a sintomatologia de dor lombar associado a uma disfunção sacroilíaca num atleta de crossfit.
Introduction: Low back pain is associated with changes in muscle activity and lumbar- pelvic kinematics caused, partly by the weakness of the core musculature. The Thomas test is widely used in clinical and sports areas to determine the shortening of the iliopsoas and rectus femoris, core constituent muscles. The shortening of these muscles is one of the risk factors for musculoskeletal injury in the lower limbs and back pain. The technique of hold-relax, increases range of motion, normalizing muscle tone. Objective: To access the effect of the hold-relax technique in the three-dimensional kinematics of the Thomas test, neuromuscular function and symptoms of a crossfit athlete with right low back pain. Methodology: Analysis of three-dimensional kinematics of the Thomas test through the capture system and 3D motion analysis, Qualisys Oqus Camera Series, and isokinetic strength of the knee by isokinetic dynamometer before and after the hold-relax technique application in a 25 years crossfit athlete. Results: After analysing the data, there was an increase in hip extension range, peak torque and reduction of pain symptoms on the affected side of the athlete, as a result of the technical application of hold-relax. Conclusion: The hold-relax technique increases range of motion andpeak torque and decreases lumbar pain symptoms associated with a sacroiliac dysfunction in a crossfit athlete.
N/A
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Finke, Mareike. "Brain mechanisms of executive control: Event-related potentials and oscillations in schizophrenic patients and healthy controls during task-switching." Doctoral thesis, Universitat de Barcelona, 2013. http://hdl.handle.net/10803/98349.
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The brain's ability to represent, maintain and update contextual (task-set) information enables us to alternate successfully between different tasks. Task-set reconfiguration is required when task demands change, as goal directed behaviour has to be adjusted to the new task. Task-cueing paradigms are widely used to investigate the underlying processes which include attentional shifting from one task to the other (task-set shifting), the retrieval of goals and rules as well as the inhibition of the previously relevant (but now irrelevant) task-set.
In the first study, different aspects regarding the extraction of cue information and its importance for task-switching processes were investigated. The main focus of interest were the electrophysiological modulations regarding changes in sensory cues which (1) are or are not related to a switch in task, or even (2) may not carry any task-relevant information in some trials. The process of early (task-relevant) change detection is important in order to prepare the upcoming task. The results suggest that cue-locked event-related potentials (ERPs) are not modulated due to purely sensory changes, but rather any such ERP modulations reflect a task-related process. At least three sub-processes were identified: (1) a fast detection of task-relevant changes (as early as 180 ms), (2) a process of cue-response mapping, and (3) the reloading/updating of stimulus-response mappings. Target-locked analyses revealed that non-informative cue switches do not affect task preparation in any significant way.
The second study consisted of the analysis of the data from study I in the time-frequency domain in order to elucidate power changes in the alpha and theta bands. We independently manipulated (1) anticipatory task preparation by manipulating the informativeness of cues about the upcoming task, and (2) the exogenous contribution to endogenous task-set switching. This design enabled us to examine the relative contribution from exogenous cue changes upon endogenous task-set reconfiguration effects, and whether those effects depend on the presence of foreknowledge about the upcoming task.
The data confirmed strong generic preparation benefits as visible in behavioural performance and both frequency bands. Task switching effects in the alpha band could be related to both goal shifting and rule activation while task switch effects in the theta band seemed related to initial task-set reconfiguration rather than task-set implementation. Strong oscillatory modulations for cue switch trials suggested an “incongruent cue-task transition” effect. Importantly, no significant effects for “task-neutral” cue switches were found.
The third study aimed to investigate higher order cognitive impairments in schizophrenia. Previously, such type of deficits has been conceptualized as failures in executive control and contextual processing. Alternatively, disturbances in high-order cognitive functions might also be due to more delimited deficits, especially in lower-level stages of contextual processing. Moreover, early processing stages do not involve only mere sensory processing, but rather reflect interacting sensory and cognitive mechanisms. Therefore, it was deemed necessary to explore the patients' task-switching abilities by manipulating sensory updating and task-set updating orthogonally to examine the interplay between bottom-up and top-down control processes. Our results suggested that the observed impairments in task-switching behaviour in schizophrenic patients were not specifically related to anticipatory set-shifting, but derived from disrupted early sensory processes of both cue- and target-locked information, as well as from a deficit in the implementation of task-set representations at target onset in the presence of irrelevant and conflicting information.Esta tesis tuvo como objetivo investigar los procesos de cambio de tarea en pacientes esquizofrénicos y controles sanos mediante un paradigma de cambio de tarea con indicadores explícitos. El estudio I examinó el uso de conocimiento previo durante el cambio de tarea, manipulando la actualización sensorial y el control ejecutivo en ensayos con indicadores informativos y no-informativos. Los cambios sensoriales en el estímulo indicador modularon los potenciales evocados (PEs) asociados al indicador sólo cuando contuvieron información conceptual sobre la tarea. La preparación para la tarea facilitó una re-asignación estímulo-respuesta ante el estímulo diana, suscitando respuestas más rápidas en todos los ensayos repetitivos. Los resultados apoyan la hipótesis de una detección rápida de los cambios sensoriales (del indicador) cuando éstos son relevantes para la tarea, y son contrarios a los beneficios por repetición de tarea debidos a una preparación (priming) perceptiva por repetición. El segundo estudio examinó las modulaciones en las oscilaciones neuronales en las bandas alfa y theta de los datos del estudio I. Los resultados también revelaron importantes beneficios en la ejecución conductual. En los ensayos de cambio de tarea durante la actualización y la implementación de la tarea, el ritmo alfa estuvo relacionado con ambos procesos evocados por el indicador sensorial y el estímulo diana, respectivamente. Por el contrario, el ritmo theta estuvo más relacionado con las etapas iniciales de la preparación de tarea. Estos dos estudios refuerzan la hipótesis de que las modulaciones en la actividad cerebral asociadas a un cambio del indicador de tarea no son provocadas por un cambio sensorial simple, sino que están relacionadas con un cambio de meta de orden superior. En el tercer estudio un protocolo de cambio de tarea con indicador explícito fue administrado a un grupo de pacientes esquizofrénicos y comparado con una muestra control sana. Los resultados sugieren que las alteraciones observadas en la conducta de cambio de tarea no estuvieron relacionadas específicamente con una reconfiguración estímulo-respuesta de orden superior, sino a un déficit en la implementación de dicha representación configuracional de la tarea durante la presentación del estímulo diana en presencia de información irrelevante y conflictiva.
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Gunby, James Alexander. "Measurement errors in case-control and related studies." Thesis, University of Oxford, 1993. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.239324.
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Thompson, David William. "Mitigating size related limitations in wind turbine control." Thesis, University of Strathclyde, 2018. http://digitool.lib.strath.ac.uk:80/R/?func=dbin-jump-full&object_id=30329.
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As the size of wind turbines steadily increase, a control system which can manage the loads and dynamics becomes more important. In this thesis, the effects of turbine scale on the control system are examined and designs which mitigate the arising problems are presented and discussed. In this thesis, a set of three wind turbines is developed using a method to scale a mathematical model of a wind turbine while maintaining similarity in the dynamics. This framework for producing the scaled wind turbines is presented and discussed. The performance of the controller for a very large wind turbine is limited by the dynamics of the tower. By accounting for the non-minimum-phase dynamics present in the wind turbine, previous work has reduced loads in the tower. In this thesis, this framework is developed to improve speed and power control and recover some of the performance lost as turbine size increases. As well as the effect of the tower, non-linear dynamics present in the pitch control loop adversely effect performance. Previous work has developed a framework for a controller for non-linear plants which satisfies a criteria called extended local linear equivalence (ELLE). A novel controller which satisfies the ELLE criteria is presented which counters the non-linear dynamics present in the wind turbine and reduces fluctuations in speed and power. A comparison of a baseline controller and a controller which incorporates the two designs described above shows significant reductions in the fluctuations of rotor and generator speed as well as power output. These changes to the controller also show greater improvements to performance in larger turbines. The inuence of the the tower and the non-linear dynamics present in the aerodynamics both become more severe as the size of the wind turbine increases. Therefore, a controller design which mitigates these effects has greater value as the wind energy industry continues on its path and develops ever larger wind turbines.
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Chernysh, Ksenia. "Stochastic average-cost control, with energy-related applications." Thesis, Heriot-Watt University, 2016. http://hdl.handle.net/10399/3194.
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In this thesis we present a new stochastic optimisation model arising from supplyside management of power networks. We provide the exact optimal solution under assumption that the environment is Markovian. For the semi-Markovian environment we establish existence of an optimal policy in an important subclass of policies. Finally, we solve the problem for a number of particular examples of environment.
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Thambidorai, Ganesh. "Multiresponse Optimization Methodology Considering Related Quality Characteristics." Thesis, North Dakota State University, 2011. https://hdl.handle.net/10365/29174.
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Engineering problems often involve many conflicting quality characteristics that must be optimized simultaneously. Engineers are required to select suitable design parameter values which provide better trade-off among all quality characteristics. Multiresponse optimization is one of the most essential tools for solving engineering problems involving multiple quality characteristics. Optimizing several quality characteristics when the quality characteristics are correlated makes the optimization process more complex. The aim of this research is to evaluate the performance of several existing multiresponse
optimization methods and investigate their capabilities in dealing with correlated quality characteristics. This study also investigates the impact of uncertainty in terms of input parameter selection. A new multi-response optimization approach has been proposed for solving correlated quality characteristics. The proposed approach is compared with the existing methods and found more robust in terms dealing with
uncertainty in target selection. The comparative study and application of the proposed approach is demonstrated by considering two examples from the literature having correlated quality characteristics.
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Touloupis, Emmanuel. "A fault tolerant microarchitecture for safety-related automotive control." Thesis, Loughborough University, 2005. https://dspace.lboro.ac.uk/2134/14402.
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The successful use of fly-by-wire systems in aviation along with the positive experience of drive-by-wire systems with mechanical backup for braking and power steering have led to the development of complete drive-by-wire systems that reduce the cost of a vehicle, are lighter and provide better passive safety to the passenger. These systems have the form of a distributed, real-time embedded system. Similar architectures can be found in other safetycritical and mission-critical applications in avionics, as mentioned before, medical equipment, and the industrial sector. The advances in embedded system technology has enabled designers to implement low-cost and small form factor electronics. However shrinking CMOS technologies are facing considerable reliability problems since they become more sensitive to transient faults. This thesis investigates the application of traditional methods for the development of safety critical computer systems and their application on single-chip devices. The contributions of this work are briefly summarised as follows: • The development of a novel fault-tolerant architecture for protecting the processor core. • Methods for performing fault-injection experiments on embedded processor architectures. • Fault-models for multiple faults on digital systems with the use of statistical distributions. • An extensive study of a processor's behaviour under the presence of faults within its pipelined execution unit.
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Forster, Martin. "Economics, inequalities in health and health-related behaviour." Thesis, University of York, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.245870.
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Chambers, C. "Industrial strength techniques for the development of PLC-based safety-related control and protection systems." Thesis, University of Sheffield, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.327619.
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Urban, Lukasz. "General sense of control not related to God presence| Implications for the compensatory control model." Thesis, Adler School of Professional Psychology, 2016. http://pqdtopen.proquest.com/#viewpdf?dispub=10168831.
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The compensatory control model has been suggested as one way of understanding the complex relationship between the experience of God and the experience of control. This model states that when one's sense of control is threatened, it can be compensated for by increased beliefs in external systems of control (such as a supreme being, or the government) that are thought to provide one with a general sense that the world is in order. Previous research has produced evidence for the compensatory control model, but has failed to consider a conceptual distinction between the personal experience of God (God Image) and the conceptual understanding of God (God Concept). A sample of 135 participants whose demographics closely resemble the population of academia took a brief internet survey measuring a dimension of God Image, and general sense of control. Statistical analysis of the correlation produced a coefficient of r = .13 that was not statistically significant. Contradicting the study hypothesis, the findings suggest that general sense of control was not related to how much one experiences God as present in his or her life. Implications for the fields of sociology, theology, and psychology are discussed.
Keywords: God image, God concept, control, compensatory control, religiosity
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Bernroider, Edward, and Milen Ivanov. "IT Project Management Control and the Control Objectives for IT and Related Technology (CobiT) Framework." Elsevier, 2011. http://dx.doi.org/10.1016/j.ijproman.2010.03.002.
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Motivated by scarce academic consideration of project management control frameworks, this article
explores usage, value and structure of frameworks with a focus on the popular Control Objectives for
IT and related Technology (CobiT) construct. We attempt to add to an empirically validated structure
of internal control over IT project management by including CobiT's views on the intended domain of
content. Results from the empirical survey indicate that the metrics suggested by CobiT are regarded
as feasible and important by project management professionals, and are regularly used in controlling
practice. Experience, regularity of significant projects and the size of the hosting organisations,
however, seem to be stronger moderators of success rates than the use of a management control
system with or without support of CobiT. CobiT's suggestions are of generic nature and in particular
useful for programme performance management. The latent dimensions of project quality on process
and activity levels were not validated and gaps to other project assessment models were identified.
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Easton-Carter, Kylie 1973. "The consequences of drug related problems in paediatrics." Monash University, Dept. of Pharmacy Practice, 2001. http://arrow.monash.edu.au/hdl/1959.1/8988.
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Gyllenqvist, Linda, and Josefine Sundqvist. "Hedersrelaterat våld : En studie om socialarbetares förståelse av hedersrelaterat våld." Thesis, Högskolan i Gävle, Avdelningen för socialt arbete och psykologi, 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:hig:diva-16364.
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After the honor killings of Fadime and Pela, an extensively discussion started in the media, debating honor-related violence and oppression. This debate also made us, the authours of this paper, to pay attention to the problem. As a professional in social work, there are several good points to be made by having an in-depth knowledge in the field, both to discover individuals exposed to honor-related violence and to be able to protect them. The study was conducted by four qualitative interviews with professionals in social work with a professional experience of honor-related problems. Through the interviews, the social worker's view of honor problems emerged. The overall aim of this paper was to analyze how professional social workers relate to the phenomenon of honor-related violence, and how the problems are made visible. A second aim was to show how social services can protect individuals exposed to honor-related violence based on current legislation. Our results demonstrate that the professionals' knowledge is critical to whether honor contexts are discovered and for its continuing work on these cases.
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Heroux, Pierre. "Publications related to the Global Positioning System Active Control Systems." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1997. http://www.collectionscanada.ca/obj/s4/f2/dsk2/ftp01/MQ30048.pdf.
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Nistazakis, Emmanouil. "Process and systems based methodologies related to control structure selection." Thesis, City University London, 1998. http://openaccess.city.ac.uk/7711/.
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This thesis is concerned with an important aspect of process control design, that is, the synthesis of the control structures. A review of the rapidly growing process methodologies' literature is presented and this leads to the identification of wider issues and new problems which are referred to as global instrumentation and forms the main subject of this thesis. The main objective has been the integration of existing process based tools and methodologies with a much more general approach of a systems and control theory character. The problem of Global Process Instrumentation concerns the selection of systems of measurement and actuation variables, found during the synthesis/design and operation of large-scale industrial processes/systems. The role of traditional instrumentation was considered but the emphasis has been on the systems aspects. In fact, instrumentation leads to the shaping of the final system and thus, is crucial in defining the control quality properties and operability characteristics of the final design. The development of these system aspects led to the emergence of an integrated framework for Global Instrumentation. An attempt was also made to abstract some results and formulate generic issues and problems, that would provide a wider scenario for activities in the future. Development of CAD to support the selection of control structures has been a major task undertaken here. The system aspects of Global Instrumentation are demonstrated by studying two specific problems that involve the study of the structural properties of interconnected systems as a function of local selection of sensors and actuators and the problem of well-conditioning badly structured transfer functions. The role of selection of inputs and outputs, on the overall shaping of composite structure properties, at the subsystem level, was examined, and the significance of an assumption related to interconnections, referred to as the completeness assumption, was investigated. Specifically, the significance of the deviations from the completeness, was the subject of the investigation. Matrix Pencil Theory was used to examine the controllability, observability and zero structure related properties of composite systems under partial or total loss of inputs/outputs at the subsystem level. Selecting subsets of the original sets of inputs, outputs to guarantee full rank transfer function, was also an issue that was examined. The above problems were presented as part of an integrated design philosophy that aims to explore the system structure. An integrated approach to the overall problem of control structure selection was formulated and open issues and problems were identified. It was based on the assumption that there exists a progenitor model of the linear type for the process, which, however, may not be well defined. Structural analysis of the system theoretic framework, the interaction measures and the results for evaluation of alternative decentralisation schemes were then used, to specify a step by step approach to the control structure selection. The problem of handling alternative criteria was also considered and basic elements of a system procedure were given. There are many open issues, which were identified and are still open and thus the proposed structural approach should be considered as the first step to the development of an integrated methodology that involves the following major steps: (a) Classification of system model variables and definition of well structured progenitor model. (b) Definition of effective input, output structure based on operability, controllability criteria. (c) Determining the structure of the control scheme by evaluation of alternative decentralised structures. An important part of the integrated methodology for control structure selection is the - so called - interaction analysis. It consists of a number of diagnostics and structural tests that help to restrict the choice of the best scheme. Several of these tests/methodologies were reviewed and some of them were further expanded. The outcomes obtained by these methodologies provided promising results. These results gave the motivation for the construction of a complete CAD package, the "Interaction Analysis Toolbox", written in MATLAB®t. This Toolbox provides many tools and diagnostics that can be applied during the design stages, for the evaluation of the various alternative control structures.
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Pias, Marcelo Rita. "Service level agreement and tariff related control of Internet metering." Thesis, University of London, 2004. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.405852.
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Zhang, Jun. "Particle matter emission control and related issues for diesel engines." Thesis, University of Birmingham, 2011. http://etheses.bham.ac.uk//id/eprint/1521/.
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The particulate matter is probably one of the most critical issues of the diesel engine emissions. After years of research, people begin to understand it further, with respect to its impact on the environment and human health, its formation mechanism inside and outside the diesel engine, and most importantly, the methods to control its formation. This study has focused on the particulate matter emission control in diesel engines. It started with the application of two closely coupled Diesel Particle Filters (DPFs), consisting of an assistant DPF and a main standard honeycomb DPF, to replace the standard Diesel Oxidation Catalyst (DOC) + DPF system, commonly applied on diesel engines these days. This new after-treatment system showed a great potential to be adopted in the future, not only for the tighter emission regulations but also for the great cost reduction of the total after-treatment system by the reduction of the main DPF’s size and weight and more options of other cheaper materials. The back pressure problem revealed in the experiment was then studied through a one dimensional model simulation and its influence to the engine performance was discussed. Fuel injection parameters which are related with the engine performance and emissions were also investigated in the study. After careful calibrations, a single injection induced Partially Charge Compression Ignition (PCCI) combustion was achieved, in which mode, NOx and smoke emissions were reduced by more than 80% compared with using the normal multiple injections. Following that, the non-volatile particulate emissions under the pilot injection’s impacts were studied and the key parameters of the pilot control such as fuel quantity and injection timing were examined. The particulate number concentrations and size distributions were investigated under different engine operation conditions and the results illustrated how a pilot injection alongside a main injection could influence particulates and what these effects were closely related to. The research continued with the investigation of bio-fuels on the particle emission reduction, when 10% alternative diesel fuel blends (Rapeseed Methyl Ester (RME) and Gas-to-Liquid (GTL)) were used. They indicated that without any modification to the engine, adding selected alternative fuels, even at a low percentage, could result in a noticeable reduction of the particle numbers, both in the total and the non-volatile parts; however, the number of nucleation mode particles could increase in certain cases. It was also revealed that the engine suffered very high numbers of the nucleation mode particulates during warming up.
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Junior, Reinaldo Squillante. "Controle relacionado à segurança nas indústrias de processos: uma abordagem integrada de modelos de acidentes, defesa em profundidade e diagnosticabilidade segura." Universidade de São Paulo, 2017. http://www.teses.usp.br/teses/disponiveis/3/3152/tde-10082017-110852/.
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A questão da segurança funcional das indústrias de processos vem recebendo uma atenção crescente pela comunidade científica mundial, uma vez que se observa a possibilidade de ocorrências de acidentes e as consequências indesejadas que estes acidentes têm provocado. Essas indústrias podem ser consideradas como parte de uma classe de sistemas denominados Sistemas Críticos, que são caracterizados pela possibilidade de ocorrência de falhas críticas, que resultam em acidentes com perdas de vidas humanas, danos ao meio ambiente e perdas financeiras envolvendo custos significativos de equipamentos e propriedades. Estes fatos justificam a necessidade de uma nova abordagem no que se refere ao design de processos, design de controle de processos, análise e controle de riscos e avaliação de riscos. Um dos desafios pertinentes à segurança funcional está associado a como vincular os cenários de acidentes aos requisitos para projetos de sistemas de controle relacionados à segurança das indústrias de processos de forma sistemática. Por sua vez, a possibilidade de ocorrência de eventos críticos e/ou eventos indesejados não observados ou ocultos, como fatores relevantes associados à evolução da sequência de eventos que culmina na ocorrência de um acidente. Neste contexto, o desafio está em aprimorar a eficácia destes sistemas de controle, que envolve o desenvolvimento de uma solução capaz de supervisionar o processo de evolução de falhas críticas, a fim de se garantir um nível de segurança funcional adequado e que esteja em conformidade com as normas internacionais aplicáveis IEC 61508 e IEC 61511. Portanto, estas considerações trazem novos requisitos para o projeto de sistemas de controle desta natureza, capaz de englobar modelos de acidentes e processos de evolução de falhas críticas. Uma solução é a consideração das abordagens de prevenção e mitigação de falhas críticas de forma integrada e interativa. Além disso é necessário abordar novas técnicas e conceitos para que se possa desenvolver um sistema de controle capaz de rastrear e atuar nos processos de evolução de falhas desta natureza. Uma possibilidade consiste em considerar o princípio de defesa em profundidade aliado à propriedade de diagnosticabilidade segura. O atendimento a este novo conjunto de requisitos não é trivial e se faz necessário integrar diferentes formalismos para o desenvolvimento de soluções adequadas. Portanto, este trabalho apresenta uma metodologia para o projeto de um sistema de controle baseado no conceito de segurança funcional para indústrias de processos, e que propõe: (i) uma arquitetura de controle para prevenção e mitigação de falhas críticas, (ii) extensão da classificação de barreiras de segurança focando na automação via sistemas instrumentados de segurança (SIS) (iii) framework para a síntese de sistemas de controle relacionados à segurança baseado em modelos de acidentes e que contempla os seguintes métodos: (a) elaboração do HAZOP, (b) construção de modelos de acidentes, (c) integração dos modelos de acidentes com o HAZOP e (d) geração dos algoritmos de defesa para a prevenção e mitigação de falhas críticas, a partir de técnicas de modelagem usando extensões da rede de Petri: Production Flow Schema (PFS) e Mark Flow Graph (MFG). A metodologia proposta foi verificada, a partir de exemplos de aplicação investigados na literatura.The issue of the functional safety of process industries has been receiving increasing attention from the world scientific community, since it has stated the possibility of occurrences of the accidents and the related undesired consequences. These industries can be considered as part of a system class called critical systems, which are characterized by the occurrence of critical faults, which can result in accidents involving loss of life, damage to the environment, and financial losses involving equipment and property. These facts justify the need for a new approach that addresses: process design, process control design, risk analysis and control, and risk assessment. One of the challenges related to functional safety is associated with how to integrate accident scenarios to the requirements for the design of safety-related control systems of the process industries in a systematic way. Furthermore, there is the possibility of the occurrence of the unobserved or hidden undesired and / or critical events, as relevant factors associated to the evolution of the sequence of the events that corroborates in the occurrence of an accident. In this context, the challenge is to improve the effectiveness of these control systems, which involves the development of a solution capable of supervising the process of evolution of the critical and / or undesired events, in order to guarantee an adequate level of functional safety, and that complies with the applicable international standards IEC 61508 and IEC 61511. Therefore, these considerations bring new requirements for the design of control systems of this nature, capable of encompassing the accident models and the critical fault evolution processes. One solution is to consider critical fault prevention and mitigation approaches in an integrated and interactive way. In addition, it is necessary to addresses new techniques and concepts in order to develop a control system capable of tracking and acting in the evolution processes of faults of this nature. One possibility is to consider the principle of defense-in-depth coupled with the property of safe diagnosability. The fulfillment of this new set of requirements is not trivial and it is necessary to integrate different formalisms for the development of adequate solutions. Therefore, this work presents a methodology for the design of a safety-related control systems based on the concept of functional safety for the process industries, which proposes: (i) a control architecture for the prevention and mitigation of the critical faults, (ii) an extension of the classification of the safety barriers focusing on automation via safety instrumented system (SIS), (iii) a framework for the synthesis of the safety-related control systems based on accident models and which includes the following methods: (a) elaboration of the HAZOP study, (b) construction of the accident models, (c) integration of the accident models with the HAZOP study, and (d) generation of the defense algorithms for the prevention and mitigation of the critical faults, via modeling techniques using extensions of the Petri net: Production Flow Schema (PFS) and Mark Flow Graph (MFG). The proposed methodology was verified, from application examples investigated in the literature.
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Crowley, Michael John Anthony. "Chemical control : exploring mechanisms for the regulation of riot control agents, incapacitants and related means of delivery." Thesis, University of Bradford, 2012. http://hdl.handle.net/10454/5717.
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A holistic arms control (HAC) analytical framework was employed to explore the full range of mechanisms that could potentially be utilised to effectively regulate the development, stockpiling, transfer or use of riot control agents (RCAs), incapacitants and related means of delivery. From this analysis it is clear that the Chemical Weapons Convention (CWC) and its attendant regime are the most appropriate and probably the most receptive mechanisms, at least in the short term, for the discussion of these concerns and the development of appropriate policy responses. However, the response of CWC States Parties to these issues is by no means certain and parallel processes should be established to explore alternative regulatory mechanisms with the Biological and Toxin Weapons Convention, UN drugs conventions, international and regional human rights instruments, international humanitarian law, and transfer controls potentially yielding positive results in the next five to ten year period. Other regimes that may well prove important in the longer term include: the international criminal court and other international criminal law entities; the UN Secretary General's investigation mechanism and other ad hoc UN investigatory mechanisms. A comprehensive HAC strategy for the regulation of RCAs, incapacitants and related means of delivery will also require active involvement of informed and activist civil society in societal verification; development and promotion of norms prohibiting the involvement of scientific and medical communities in weaponisation programmes intended for malign application; and far greater active engagement of such expert communities in relevant State and international policy development processes.
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Crowley, Michael J. A. "Chemical control. Exploring mechanisms for the regulation of riot control agents, incapacitants and related means of delivery." Thesis, University of Bradford, 2012. http://hdl.handle.net/10454/5717.
Full textAbstract:
A holistic arms control (HAC) analytical framework was employed to explore the full range of mechanisms that could potentially be utilised to effectively regulate the development, stockpiling, transfer or use of riot control agents (RCAs), incapacitants and related means of delivery. From this analysis it is clear that the Chemical Weapons Convention (CWC) and its attendant regime are the most appropriate and probably the most receptive mechanisms, at least in the short term, for the discussion of these concerns and the development of appropriate policy responses.
However, the response of CWC States Parties to these issues is by no means certain and parallel processes should be established to explore alternative regulatory mechanisms with the Biological and Toxin Weapons Convention, UN drugs conventions, international and regional human rights instruments, international humanitarian law, and transfer controls potentially yielding positive results in the next five to ten year period. Other regimes that may well prove important in the longer term include: the international criminal court and other international criminal law entities; the UN Secretary General¿s investigation mechanism and other ad hoc UN investigatory mechanisms.
A comprehensive HAC strategy for the regulation of RCAs, incapacitants and related means of delivery will also require active involvement of informed and activist civil society in societal verification; development and promotion of norms prohibiting the involvement of scientific and medical communities in weaponisation programmes intended for malign application; and far greater active engagement of such expert communities in relevant State and international policy development processes.
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Sengupta, Ayesha. "Mechanisms of serotonergic control in fear-related neural circuits and behaviour." Thesis, University of Oxford, 2017. https://ora.ox.ac.uk/objects/uuid:333590cf-964d-44dd-8f5b-4d492e15f8b2.
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Serotonin (5-HT) neurotransmission is strongly implicated in affective psychopathologies, with first-line drugs selectively targeting the 5-HT system. Further evidence for the role of 5-HT as an important regulator of emotional states comes from human gene association studies. These have identified polymorphic variants of the 5-HT transporter (5-HTT) gene with reduced transcription efficacy. Lower 5-HTT expression associates with susceptibility to affective disorders and heightened amygdala reactivity to fearful stimuli. The mechanisms by which 5-HTT gene variation leads to altered amygdala function and fear-related behaviour are unknown. The experiments presented in this thesis study these associations in tractable animal models that allow temporal- and circuit-specific control over 5-HT signalling. Specifically, a translationally relevant mouse model of 5-HTT expression variation and an optogenetic approach are used to probe how changes in 5-HT transmission shape fear-related behaviours. Using an array of behavioural tests, it was found that 5-HTT overexpressing (OE) mice exhibit a low-fear/anxiety phenotype that is already established in adolescence, indicating a possible neurodevelopmental trajectory. Acute pharmacological blockade of the 5-HTT at the time of behavioural testing did not rescue the low-fear phenotype in adolescent 5-HTT OE mice, whereas 5-HTT blockade during an early postnatal period did reverse it. These results identify a developmental origin of the fear-related phenotype associated with 5-HTT expression variation. Next, in vivo optogenetic tools were employed during a fear learning task to control neuromodulation of the basal amygdala (BA) by 5-HT neurons arising from the dorsal raphe (DRN). Photoexcitation of the DRN-BA 5-HT projection pathway enhanced fear learning and impaired fear extinction, while photoinhibition caused a fear learning deficit and facilitated fear extinction. Thus, a bidirectional functional role in fear learning for the BA-targeting 5-HT pathway was characterised. The effect of optogenetic photoexcitation of the DRN-BA 5-HT pathway on BA single unit and network activity during the fear learning task was then recorded in vivo. The study revealed that 5-HT projection activation promoted a neurophysiological state (both in terms of individual neuron activity and network oscillations) in the BA that has previously been associated with fear expression. Ex vivo electrophysiology experiments then explored the effect of optogenetic activation of the DRN-BA 5-HT pathway on the BA microcircuitry. These latter experiments identified clear evidence of 5-HT and glutamate co-transmission within the BA, which functioned in a cell type-specific and frequency-dependent manner. Finally, a combination of retrograde tracing and immunohistochemistry was applied to analyse the neurochemical identity of DRN neurons that project to the BA. The majority of these neurons were found to co-express markers for 5-HT and glutamate. To evaluate the contribution of 5-HT transmission from DRN-BA 5-HT projections to fear learning, optogenetics was combined with local infusion of 5-HT receptor antagonists. This experiment demonstrated that photoexcitation-induced enhancement of fear learning was mediated by 5-HT-dependent mechanisms. In summary, this thesis presents new evidence that DRN-BA 5-HT projections exert circuit-, temporal-, and 5-HT receptor-specific regulation of fear-related behaviour. These results highlight the importance of elucidating precise actions of 5-HT transmission in moving towards a more accurate understanding of how the 5-HT system influences emotional states.
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Molavi, M. A. "A study of potash mining methods related to ground control criteria /." Thesis, McGill University, 1987. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=66262.
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Wu, Lap-kei, and 胡立基. "Control of syndecan-1 shedding to limit smoking-related neutrophilic inflammation." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2015. http://hdl.handle.net/10722/211108.
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Li, Yapeng. "Dynamic energy demand prediction and related control system for UK households." Thesis, University of Newcastle upon Tyne, 2015. http://hdl.handle.net/10443/2824.
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Domestic energy consumption is not only based on the type of appliances, weather conditions, and house type; it is also highly depended on related occupancy profiles. In order to manage and optimise energy generation and the effective use of energy storage, it is important to be able to accurately predict energy demand in advance. However, high-resolution (like below 1-min) occupancy profiles for domestic UK households are not ideally possible to be recorded or measured in nature. Therefore, an alternative approach to transfer particular electricity load to the number of active occupancy during selected time interval is identified by analysing the average electricity consumption of occupancy in this study. Real load data analysis for three type of participated UK households is presented throughout the year. Then the seasonal synthetic high-resolution (30s) occupancy patterns for each household are generated independently. Weekday occupancy profiles are collected seasonally and used in a Markov-Chain model to produce particular occupancy daily activity sequence for each household. A stochastic model by using Markov-Chain Monte Carlo is presented to randomly generate high-resolution occupancy profiles in dynamic. Then the predicted electricity loads are produced by mapping occupancy profiles to average electricity consumption. By validating the predicted results, it is found that maximum of sub-hourly aggregate result can mostly cover the measured demand in advance. Therefore, it is set the sub-hourly electricity demand boundary independently for each household during weekday throughout the year. Heat demand for each household is simulated in sub-hourly resolution by using DesignBuilder with EnergyPlus throughout the year. Thus, sub-hourly energy demand of each household is applied in the control system of Bio-fuel Micro Trigeneration with Hybrid Electrical Energy Storage. The control system is designed and implemented by using Siemens software STEP-7 S-300 and WinCC. In addition, the predicted energy demands are utilized into the optimization of the control system. The comparison of optimized and general control strategies shows that optimized strategies by applying prescient sub-hourly energy demand can improve system efficiency significantly.
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Sowell, Robin E. "Toward a General Model of Social Control and School Related Violations." W&M ScholarWorks, 1991. https://scholarworks.wm.edu/etd/1539625703.
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Botello, Jesus. "Combat-Related Posttraumatic Stress Disorder: Locus of Control and Marital Satisfaction." ScholarWorks, 2015. https://scholarworks.waldenu.edu/dissertations/134.
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Combat-related posttraumatic stress disorder (PTSD) is a psychological condition researchers have cited as a major cause of marital discord and divorce for veterans with PTSD. This study examined the psychological construct of locus of control among the wives of veterans diagnosed with combat-related PTSD and whether or not it was a predictor of marital satisfaction within this context. An extensive search of the current literature revealed no previous studies that had investigated this relationship. Utilizing the family systems theory to address this gap, this study sought to compare reported marital satisfaction in wives with an internal locus of control to those with an external locus of control. Participants for this study were 111 wives of veterans with combat-related PTSD, each of whom completed a demographic questionnaire, the Kansas Marital Satisfaction Survey, and the Duttweiler Internal Control Index. A multiple linear regression was conducted to determine if age, number of years married, number of children, level of education, household income, and internal locus of control were predictors of marital satisfaction reported by wives of veterans with combat-related PTSD. The results indicated that an internal locus of control accounted for a significant degree of the variance in marital satisfaction while the demographic variables were not significant predictors. This study contributes to social change by providing an empirical insight into the relationship between locus of control and marital satisfaction in wives of veterans with PTSD. The results of this study could help improve the quality of life of veterans with PTSD by enhancing awareness of locus of control to practitioners while developing a therapeutic treatment plan that will fit the veteran's locus of control orientation.
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Elchlepp, Heike. "The temporal dynamics of switching tasks." Thesis, University of Exeter, 2011. http://hdl.handle.net/10036/3233.
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The topic of this thesis is cognitive control: how the brain organises itself to perform the many tasks it is capable of and how it switches flexibly among them. Task-switching experiments reveal a substantial cost in reaction time and accuracy after a switch in tasks. This "switch cost" is reduced by preparation (suggesting anticipatory task-set reconfiguration), but not eliminated. The thesis focuses on the sources of the "residual" cost. Most accounts attribute it to response selection being prolonged on a task-switch trial by task conflict, e.g. by 'task-set inertia' — persisting activation/inhibition of the previous task's S-R rules — or their associative reactivation by the stimulus. Four experiments used event-related potentials (ERPs) to determine which stages of task processing are influenced by a change in tasks, looking for delays in process-specific markers in the ERP. Experiments 1 and 2 showed that a prepared switch to a reading task from a perceptual judgement delayed early ERP markers of lexical access by a large fraction of the RT switch cost, suggesting that a substantial part of the residual cost arises in processes earlier than response selection, possibly due to task-related attentional inertia. Markers of lexical access observed in the non-lexical task were larger on switch than repeat trials, providing the first electrophysiological evidence of task-set inertia. Experiment 3 examined the effects of an unprepared switch in the same way. ERP waveforms were modulated by a switch before markers of lexical access were evident, suggesting additional processing demands compete for resources with lexical access. A simple delay, however, was not found; post-stimulus task-set reconfiguration does not just insert an extra processing stage. Experiment 4 looked for a delay in the onset of an early ERP marker of emotional processing when the task switched between categorising facial expression and classifying a superimposed letter. No such delay was found in this case, and ERP markers of emotion processing were present to the same extent in the letter task. This suggests that, given appropriate spatial attention, processing facial emotion unfolds automatically, independent of attention allocation to the facial features. Experiments 5-7 further explored the link between conflict due to processing the irrelevant stimulus dimension and the ERP post-stimulus negativity that accompanies the residual cost. The negativity could be elicited even on trials of non-switching blocks by prior training on classifying the irrelevant attribute of the stimulus using the same responses. But this effect did not seem to result from the trained class of irrelevant attribute attracting more attention. Finally, Experiment 8 followed up an incidental observation in Experiment 1 to establish the novel observation that a task-switching context abolishes the usual ERP correlate of withholding a response in a go/no-go paradigm, suggesting an interesting interaction between task-set control and response inhibition.
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Sjöberg-Linna, Annica. "Krav och Kontroll på arbetet : - vilka förklaringsvariabler påverkar individens upplevelse?" Thesis, Mälardalens högskola, Akademin för hållbar samhälls- och teknikutveckling, 2011. http://urn.kb.se/resolve?urn=urn:nbn:se:mdh:diva-14152.
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Arbetsmiljön kan enligt Karasek och Theorell (1990) karaktäriseras i två dimensioner, psykologiska krav från arbetet och i vilken utsträckning individen möter dessa med hjälp av egenkontrollen. De har utvecklat krav-kontroll modellen som mäter den psykosociala arbetsmiljön. Modellen används i denna studie för att undersöka huruvida några förklaringsvariabler relaterar till individens upplevelse av krav och kontroll på arbetet. Deltagarna fick besvara en enkät besående av olika variabler och självskattningsskalor som mätte krav och kontroll. Även känslan av sammanhang mättes med 13 frågor (Antonovsky, 1993). Deltagarna bestod av 116 anställda på två arbetsplatser i Västmanlands län. Resultatet visade att vissa dimensioner av förklaringsvariablerna (demografiska, arbets-, hälso och KASAM) bidrog till viss förklarad varians med avseende på krav och kontroll. Den psykiska hälsan hade ett positivt samband med kontroll och negativt samband med krav. Enligt Theorell (2003) mår individer med hög kontroll vanligtvis bättre än individer som uppleverlåg kontroll.
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Lilly-Weber, Jeanne M. "Dealing with nuclear-related emotions : an investigation of the despair and empowerment process /." The Ohio State University, 1986. http://rave.ohiolink.edu/etdc/view?acc_num=osu1487322984316999.
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Moser, Jason Scot. "Intentional regulation of negative emotions is reflected in event-related brain potentials." Access to citation, abstract and download form provided by ProQuest Information and Learning Company; downloadable PDF file 0.59 Mb., 38 p, 2006. http://gateway.proquest.com/openurl?url_ver=Z39.88-2004&res_dat=xri:pqdiss&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&rft_dat=xri:pqdiss:1435829.
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Chou, Fang-Chi. "Behavioral and electrophysiological observations of attentional control in children who stutter." Diss., University of Iowa, 2014. https://ir.uiowa.edu/etd/4593.
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Both theoretical models and empirical evidence implicate the combined influences of high emotional reactivity and low emotional regulation to exacerbation in children's stuttering behavior (e.g., Conture, Walden, Arnold, Graham, Hartfiled, Karrass, 2006; Conture & Walden, 2012; Karrass et al., 2006). Attentional control is a key factor in both the development and implementation of emotional regulation (Bell & Calkins, 2012; Rueda, Posner, & Rothbart, 2004). The purpose of this study was to investigate attentional control along the distraction process in children who stutter using two event-related potential (ERP) experimental tasks: auditory-auditory distraction and visual search. Eight school-age children who stutter (CWS) and eight school-age children who do not stutter (CWNS) were recruited in this study. Using a Go/No Go paradigm, children in this study were asked to discriminate tone duration in the auditory-auditory distraction task and detect specific visual targets in the visual search task in both the auditory and visual tasks. Behavioral measures included reaction time (RT), hit rate (HR, accuracy) and false alarm (FA), while electrophysiological measures included the peak latency and mean amplitude of the mismatch negativity (MMN), P3a, N2pc and reorientation negativity (RON), and N2pc.
Each ERP component reflects a specific stage along the distraction process: automatic scanning and change detection (MMN), involuntary orientation to deviants (P3a), attentional filtering (N2pc) and voluntary attentional reorientation (RON). The first three components are involved in the sensory/perceptual processing, while the last component is involved in the goal-directed processing (cognitive control for distraction compensation). These behavioral and ERP results were correlated with temperament data obtained from parent-report questionnaires.
There were three main findings. First, CWS, but no CWNS, exhibited a P600 and increased peak latency of the late phase of RON (lRON). The P600 is elicited by violations in rule-governed sequences or the effect of encountering unexpected stimuli, while the lRON reflects evaluation of task-relevant information and motor preparation. The existence of P600 suggests that CWS return and re-evaluate deviants, perhaps due to reduced inhibitory control. As a result, CWS are delayed to start the attentional process reflected by lRON. Second, CWS exhibited a higher rate of false alarms in the auditory-auditory distraction task; this finding confirmed the notion of less efficiency in inhibitory control for CWS. Third, similar to previous research findings, our temperament data also revealed that CWS tended to exhibit relatively high negative affect in combination with relatively low effortful and attentional control, compared to their fluent peers.
Taken together, present findings corroborate previous observations of relatively high emotional reactivity and relatively low efficiency in emotional regulation for CWS, including attentional and inhibitory control. Further, our results reveal that the low attentional control in CWS may result from less efficiency in the goal-directed processing for distraction compensation.
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Tannetta, Dionne. "Inhibin-related peptides in sheep and cattle : evidence for intraovarian actions and interactions with other regulatory systems." Thesis, University of Reading, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.360067.
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Olofsson, Marcus. "Optimal Switching Problems and Related Equations." Doctoral thesis, Uppsala universitet, Analys och sannolikhetsteori, 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-247298.
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This thesis consists of five scientific papers dealing with equations related to the optimal switching problem, mainly backward stochastic differential equations and variational inequalities. Besides the scientific papers, the thesis contains an introduction to the optimal switching problem and a brief outline of possible topics for future research. Paper I concerns systems of variational inequalities with operators of Kolmogorov type. We prove a comparison principle for sub- and supersolutions and prove the existence of a solution as the limit of solutions to iteratively defined interconnected obstacle problems. Furthermore, we use regularity results for a related obstacle problem to prove Hölder continuity of this solution. Paper II deals with systems of variational inequalities in which the operator is of non-local type. By using a maximum principle adapted to this non-local setting we prove a comparison principle for sub- and supersolutions. Existence of a solution is proved using this comparison principle and Perron's method. In Paper III we study backward stochastic differential equations in which the solutions are reflected to stay inside a time-dependent domain. The driving process is of Wiener-Poisson type, allowing for jumps. By a penalization technique we prove existence of a solution when the bounding domain has convex and non-increasing time slices. Uniqueness is proved by an argument based on Ito's formula. Paper IV and Paper V concern optimal switching problems under incomplete information. In Paper IV, we construct an entirely simulation based numerical scheme to calculate the value function of such problems. We prove the convergence of this scheme when the underlying processes fit into the framework of Kalman-Bucy filtering. Paper V contains a deterministic approach to incomplete information optimal switching problems. We study a simplistic setting and show that the problem can be reduced to a full information optimal switching problem. Furthermore, we prove that the value of information is positive and that the value function under incomplete information converges to that under full information when the noise in the observation vanishes.
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Rüb, Cornelia [Verfasser]. "The Parkinson’s disease-related kinase Pink1 mediates mitochondrial quality control / Cornelia Rüb." Bonn : Universitäts- und Landesbibliothek Bonn, 2016. http://d-nb.info/1119888662/34.
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Goldstone, Mark Edward. "The behaviour and control of motor vehicle related pollutants in urban air." Thesis, Imperial College London, 1993. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.260759.
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Latz, Anne [Verfasser]. "Neural correlates of age-related changes in cognitive action control / Anne Latz." Düsseldorf : Universitäts- und Landesbibliothek der Heinrich-Heine-Universität Düsseldorf, 2019. http://d-nb.info/1188462121/34.
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Persson, Emma. "Causal inference and case-control studies with applications related to childhood diabetes." Doctoral thesis, Umeå universitet, Statistik, 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-94993.
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This thesis contributes to the research area of causal inference, where estimation of the effect of a treatment on an outcome of interest is the main objective. Some aspects of the estimation of average causal effects in observational studies in general, and case-control studies in particular, are explored. An important part of estimating causal effects in an observational study is to control for covariates. The first paper of this thesis concerns the selection of minimal covariate sets sufficient for unconfoundedness of the treatment assignment. A data-driven implementation of two covariate selection algorithms is proposed and evaluated. A common sampling scheme in epidemiology, and when investigating rare events, is the case-control design. In the second paper we study estimators of the marginal causal odds ratio in matched and independent case-control designs. Estimators that, under a logistic regression model, utilize information about the known prevalence of being a case is examined and compared through simulations. The third paper investigates the particular situation where case-control sampled data is reused to estimate the effect of the case-defining event on an outcome of interest. The consequence of ignoring the design when estimating the average causal effect is discussed and a design-weighted matching estimator is proposed. The performance of the estimator is evaluated with simulation experiments, when matching on the covariates directly and when matching on the propensity score. The last paper studies the effect of type 1 diabetes mellitus (T1DM) on school achievements using data from the Swedish Childhood Diabetes Register, a population-based incidence register. We apply theoretical results from the second and third papers in the estimation of the average causal effect within the T1DM population. A matching estimator that accounts for the matched case-control design is used.
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Lopez, Eliot Jay. "Perceptions of Control and Social Support: Correlates of HIV-Related Self-Efficacy." Thesis, University of North Texas, 2011. https://digital.library.unt.edu/ark:/67531/metadc68003/.
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This study examines the extent to which locus of control and social support are linked to self-efficacy with regard to disease management in HIV-positive adults. Perceived ability to effectively manage illness was measured with the Self-Efficacy for Managing Chronic Disease Scale. Scores from the Multidimensional Scale of Perceived Social Support and the Multidimensional Locus of Control Scale were used as predictors. The gender-balanced sample (N = 69) of HIV+ adults was primarily African-American (65.3%) and European American (30.5%), with a mean age of 47 years (SD = 8.37). Correlational analyses suggested significant positive relationships between self-efficacy, social support, and locus of control due to powerful others. A regression analysis found that the model accounted for 23% of the variance in self-efficacy (adj. R-squared =.23, F (5, 63) = 4.81, p < .01), with social support (β = .37, t = 3.28, p < .01) and locus of control (β = .25, t = 2.26, p < .05) both significant predictors. Results suggest that social support and locus of control contribute to the belief that HIV can be managed. Interestingly, an external locus of control contributed to this belief, perhaps due to the perception of a physician, religious icon, or partner as a "powerful other." Results suggest that a strong supportive relationship with a trusted other along with enhanced social support typically associated with group-based interventions may improve health outcomes by increasing self-efficacy in disease management in HIV-positive adults.
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Pike, Erika. "THE INFLUENCE OF COCAINE-RELATED IMAGES ON INHIBITORY CONTROL IN COCAINE USERS." UKnowledge, 2017. http://uknowledge.uky.edu/psychology_etds/120.
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Cocaine users display impaired inhibitory control. The influence of cocaine-related stimuli on inhibitory control has not been assessed. The Attentional Bias-Behavioral Activation (ABBA) task uses cocaine and neutral images as cues to determine if drug-related images impair inhibitory control in cocaine users. This dissertation was designed to assess the influence of cocaine images on inhibitory control in cocaine users through the conduct of studies designed to address four aims. The first aim was to demonstrate that cocaine users display impaired inhibitory control following cocaine images compared to neutral images on the ABBA task. This was accomplished through the conduct of two experiments. The first experiment piloted the ABBA task and cocaine users completed the cocaine go (n = 15) or neutral go condition (n = 15) of the task. The second experiment consisted of two studies designed to develop a within-subjects methodology for using the ABBA task. In the first study, cocaine users completed either the cocaine go (n = 20) or neutral go (n = 20) condition of the ABBA task and all participants also completed the Cued Go/No-Go task, with geometric shapes as cues. In the second study, cocaine users (n = 18) completed the cocaine go condition of the ABBA task and a modified version of the ABBA task with all neutral images as cues to further refine a possible within-subjects methodology. The second aim was to demonstrate that inhibitory failures occur most often when cues are presented for short compared to longer durations of time. Data collected during other protocols (n = 91) were combined to investigate the influence of stimulus onset asynchrony (SOA; i.e., the amount of time a cue is presented before a target indicated a response should be executed or withheld) on inhibitory control following cocaine-related and neutral cues on the ABBA task. The third aim was to demonstrate impaired inhibitory control following cocaine images on the ABBA task is specific to cocaine users. Cocaine users (data collected in the second experiment of the first aim) and non-using control participants (n = 16) completed the cocaine go and all neutral conditions of the ABBA task and the Cued Go/No-Go task. The fourth aim was to demonstrate the feasibility and acceptability of inhibitory control training to cocaine-related stimuli with cocaine users. A small pilot clinical trial was conducted and cocaine users were randomly assigned to complete inhibitory control training to cocaine images or geometric shapes. Cocaine images impaired inhibitory control on the ABBA task, as demonstrated by an increased proportion of inhibitory failures in the cocaine go condition compared to the neutral go condition in Experiments 1, 2, and 4. The proportion of inhibitory failures following cocaine images in Experiment 4 was increased at short (i.e., 100, 200) compared to long SOAs. Cocaine images also impaired inhibitory control compared to the Cued Go/No-Go Task in Experiment 2, however there were no differences in the proportion of inhibitory failures between the cocaine go and all neutral conditions of the ABBA task. There were no differences between cocaine users and controls in Experiment 3 for the proportion of inhibitory failures on the ABBA or Cued Go/No-Go tasks, but controls responded faster indicating a speed/accuracy trade off occurred in the control group. Inhibitory control training as an approach to improve treatment outcomes is feasible, as indicated by attendance and accuracy on the training task, and participants rated the overall procedure as satisfactory in Experiment 5. A better understanding of inhibitory control in the presence of cocaine related cues could be crucial to better understand how drug cues contribute to the risk for relapse and the continued use of drugs because both occur in the presence of drug cues.
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Fuller, David Dwight 1970. "Respiratory-related control and functional significance of tongue protrudor and retractor muscles." Diss., The University of Arizona, 1998. http://hdl.handle.net/10150/282801.
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The mammalian upper airway includes the larynx, pharynx, and nose. Respiratory-related contraction of the skeletal muscles situated in and around these regions influences upper airway diameter and compliance. The pharynx is the most collapsible upper airway segment, and its diameter and compliance depend in part on tongue position and stiffness. These parameters are controlled by the genioglossus (GG) muscle, which protrudes the tongue, and the hyoglossus (HG) and styloglossus (SG) muscles, which retract the tongue. Prior work has focused almost exclusively on the GG, leaving a gap in the literature regarding the respiratory control and function of the tongue retractors. Accordingly, our overall purpose was to test the hypothesis that the tongue protrudor and retractor muscles are co-activated during inspiration and that co-activation promotes airway patency. Experiments were conducted using supine, anesthetized, tracheotomized rats. Tongue movements were quantified as either protrusive or retractive by connecting the tip of the tongue to a force transducer. The protrudor and retractor muscles were co-activated during quiet breathing and their activities increased in parallel when breathing was stimulated with high CO2 or low O 2. Co-activation of protrudor and retractor muscles was always accompanied by tongue retraction. Neural drive to both GG and HG muscles was increased in parallel when lung volume feedback was removed by single breath tracheal occlusion. The functional significance of tongue muscle co-activation was examined using an isolated upper airway preparation. Co-activation increased airflow rates and stiffened the airway, whereas selective protrudor muscle activation increased airflow but did not alter airway stiffness. A standard fatigue protocol was used to examine the influence of hypoxia on the endurance performance of tongue protrudor and retractor muscles; the results indicate that hypoxia attenuates tongue muscle endurance, possibly via impaired neuromuscular transmission. It is concluded that, in the rat, (1) the tongue protrudor and retractor muscles are co-activated during inspiration, and respond in parallel to increases in respiratory drive; (2) tongue muscle co-activation results in tongue retraction and stiffening of the pharyngeal airway, and (3) the endurance of the tongue muscles is impaired during hypoxia.
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Ruane, Deirdre. "Trip hazards : drug-related crisis, peer support and control at transformational festivals." Thesis, University of Kent, 2017. https://kar.kent.ac.uk/66261/.
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In the growing global scene surrounding transformational festivals, psychedelics and other 'party drugs' are used to facilitate experiences of connection and sociability which their devotees see as antidotes to the increasing isolation of society as a whole. Yet the openness and suggestibility that potentiates these experiences can also cause painful, alienating 'psychedelic crises'. Peer support projects within the scene attempt to address this problem by providing 'care spaces': comfortable, lower-stimulus areas within events where support workers known as 'sitters' seek to resolve service users' crises into reintegration with the collective while reducing any harm arising from their drug use. Yet within national and international drug policy frameworks which enforce prohibition and promote abstinence, the care spaces' support of harm reduction approaches to drug crisis care and their beliefs in the potential benefits of psychedelics can bring them into conflict with the authorities and with festival organisers wary of being seen to 'condone drugs'. This complex situation offers fresh perspectives on the relationships between 'party' drug use, drug policy and harm, yet these projects remain almost entirely unstudied. This thesis examines the cultural role and value system of the transformational scene, and the distinctive patterns of drug use which occur there; investigates how volunteer psychedelic support/harm reduction (PS/HR) projects address the problem of the psychedelic crisis, and the role their identity as scene peers (and often drug users) plays in their work; and finally explores the turbulent intersection between the care spaces and the policy environments in which they operate. It uses a multimodal ethnographic approach centring on participant observation as a care space sitter at events in Portugal, the UK and the US, supplemented by 23 in-depth interviews with sitters and an online qualitative survey of 54 festivalgoers who had undergone a drug-related crisis. It concludes that the festival environments are both shaped by, and designed to heighten, psychedelic experiences which many festivalgoers see as transformative and highly significant. Relatedly, scene members stress the importance of using the drugs 'respectfully' and responsibly. The desire to manifest such responsibility in a tangible way is a key motivation for sitters. Their identity as scene peers is a powerful asset in their work, helping them establish trust with visitors and assess their cases accurately while lending credibility to the drug information they distribute. However, in prohibition-based policy environments their identity as drug users can become a liability in dealings with the authorities, and networks of festival support staff can become fragmented by under-resourcing, miscommunication and the effects of stigma. Combined with ways in which punitive policy makes responsible drug use behaviours difficult to engage in, this serves to illuminate how drug policies nominally intended to increase the safety of events in fact often exacerbate harm and obstruct the efforts of those attempting to reduce it. In so doing, it extends current understandings of 'recreational' drug use and its contexts.