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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
481

Mecanismos de autoconfiguração e auto-otimização para arquiteturas virtualizadas que visam a provisão de qualidade de serviço / Mechanisms of self-configuration and self-ptimization for virtualized architectures aiming at the provision of quality of service

Nakamura, Luis Hideo Vasconcelos 19 April 2017 (has links)
A proposta deste projeto de doutorado envolve a pesquisa sobre computação autônoma, focando na elaboração de mecanismos de autoconfiguração e auto-otimização para arquiteturas virtualizadas que buscam garantir a provisão de qualidade de serviço. Esses mecanismos fazem uso de elementos autônomos que são auxiliados por uma ontologia. Para isso, instrumentos de Web Semântica são utilizados para que a ontologia represente uma base de conhecimento com as informações dos recursos computacionais. Tais informações são utilizadas por algoritmos de otimização que, baseados em regras pré-definidas pelo administrador, tomam a decisão por uma nova configuração do sistema que vise a otimizar o desempenho. A configuração e a otimização geralmente envolvem elementos de software que precisam ser gerenciados pelos profissionais em Tecnologia da Informação (TI). Parte desse gerenciamento é composto de tarefas corriqueiras, por exemplo, monitorações, reconfigurações e verificações de desempenho. Tais tarefas demandam tempo e, portanto, geram custos e desgastes para os profissionais. Dessa forma, este projeto visa automatizar algumas dessas tarefas corriqueiras, facilitando o trabalho dos profissionais de TI e permitindo que eles foquem em tarefas mais críticas. Portanto, para alcançar esse objetivo foi realizado um estudo e a criação de mecanismos distribuídos baseados em Computação Autônoma e Web Semântica que permitem a configuração e otimização de recursos de forma automática. Os resultados individuais de cada mecanismo indicam que é possível alcançar um nível satisfatório de auto-configuração e auto-otimização para arquiteturas virtualizadas. O mecanismo de auto-configuração obteve melhores resultados com a abordagem de monitoração de recursos ao invés de utilizar previsões, já o mecanismo de auto-otimização provou que sua metodologia e algoritmo são aplicáveis na busca de uma configuração otimizada para atender ao SLA acordado. / The purpose of this PhD project involves the research about autonomic computing, focusing on the development of self-configuration and self-optimization mechanisms for virtualized architectures that aims to ensure the provision of Quality of Service. These mechanisms make use of autonomous elements that are aided by an ontology. Therefore, SemanticWeb tools are used in order to allow the ontology to represent a knowledge base with information of the computational resources. Such information is used by optimization algorithms that take the decision of choosing a new configuration that aims at optimizing the architecture performance based on rules predefined by the administrator. The configuration and optimization usually involve elements of software that must be managed by professionals in the Information Technology (IT) field and part of this management is composed of common tasks, for example, monitoring tests, reconfigurations and performance evaluations. These tasks take some time and therefore generate costs and distress to the professionals. Thus, this project aims at automating some of these common tasks, facilitating the work of IT professionals and allowing them to focus on more critical tasks. Therefore, to achieve this goal a study was performed and distributed mechanisms based on Autonomic Computing and Semantic Web were created allowing the configuration and optimization of resources automatically. The individual results of each mechanism indicate that it is possible to achieve a satisfactory level of self-configuration and self-optimization for virtualized architectures. The self-configuration mechanism has achieved better results with the resource monitoring approach rather than using predictions and the self-optimization mechanism has proven that its methodology and algorithm are applicable in the search for an optimized configuration to meet the SLA agreed.
482

Interocezione. La dimensione interna del Se. / INTEROCEPTION. THE INNER DIMENSION OF THE SELF

DI LERNIA, DANIELE 02 April 2019 (has links)
L’interocezione è definita come il senso della condizione fisiologica dell’intero organismo. Le sensazioni interocettive comprendono un ampio raggio di funzioni biologiche sia consce sia inconsce, e costituiscono la dimensione interna del nostro senso del Se. L’obiettivo primario di questa tesi è stato di capire come le percezioni interne del corpo siano in grado di modificare il nostro senso del se e come questi processi possano essere cambiati, modificati e alterati per migliorare il benessere psicofisiologico. Gli scopi di questa dissertazione sono stati 1) capire come gli input interocettivi sono processati e come contribuiscono al nostra percezione del se e al nostro benessere. 2) sviluppare nuove tecnologie per manipolare il sistema interocettivo al fine di promuovere il benessere. 3) testare queste nuove tecnologie interocettive su soggetti sani e su popolazioni cliniche. La tesi propone nuovi contributi sia teorici sia sperimentali. Nella sezione sperimentale, le tecnologie interocettive sono state testate per promuovere il benessere in popolazioni cliniche e non. I risultati hanno indicato che i trattamenti interocettivi possono promuovere il benessere nei soggetti sani e ridurre la severità dei sintomi in soggetti patologici (i.e., con dolore cronico) confermando la possibilità di manipolare la dimensione interocettiva per promuovere il benessere dell’individuo. / Interoception can be defined as the sense of the physiological condition of the entire organism (Craig, 2003). From this point of view interoceptive sensations entail a broad range of relevant biological functions that serve conscious and unconscious processes and constitute the embodied inner dimension of our sense of Self. The main objective of this thesis was to understand how the perceptions that arise from our body are able to shape our sense of Self and moreover, how these processes can be changed, modified, and altered to improve both our physiological both our psychological well-being. The purpose of this dissertation was 1) to understand how interoceptive inputs are processed and how they contribute to our self-perception and well-being. 2) to develop new interoceptive technologies to manipulate the interoceptive system to promote well-being. 3) to test these new technological applications on healthy and clinical populations. The thesis proposes both theoretical both experimental contributes. In the experimental section interoceptive technologies are tested to promote well-being in healthy and clinical populations. Results indicated that “interoceptive treatment” can both promote well-being in healthy subjects both reduce symptoms severity in clinical subjects (i.e. chronic pain) confirming the possibility to manipulate the interoceptive dimension to enhance healthy functioning.
483

Generic monitoring and reconfiguration for service-based applications in the cloud / Supervision et reconfiguration génériques des applications à base de service dans le nuage

Mohamed, Mohamed 07 November 2014 (has links)
Le Cloud Computing est un paradigme émergent dans les technologies de l'information. L'un de ses atouts majeurs étant la mise à disposition des ressources fondée sur le modèle pay-as-you-go. Les ressources Cloud se situent dans un environnement très dynamique. Cependant, chaque ressource provisionnée offre des services fonctionnels et peut ne pas offrir des services non fonctionnels tels que la supervision, la reconfiguration, la sécurité, etc. Dans un tel environnement dynamique, les services non fonctionnels ont une importance critique pour le maintien du niveau de service des ressources ainsi que le respect des contrats entre les fournisseurs et les consommateurs. Dans notre travail, nous nous intéressons à la supervision, la reconfiguration et la gestion autonomique des ressources Cloud. En particulier, nous mettons l'accent sur les applications à base de services. Ensuite, nous poussons plus loin notre travail pour traiter les ressources Cloud d'une manière générale. Par conséquent, cette thèse contient deux contributions majeures. Dans la première contribution, nous étendons le standard SCA (Service Component Architecture) afin de permettre l'ajout de besoins en supervision et reconfiguration à la description des composants. Dans ce contexte, nous proposons une liste de transformations qui permet d'ajouter automatiquement aux composants des facilités de supervision et de reconfiguration, et ce, même si ces facilités n'ont pas été prévues dans la conception des composants. Ceci facilite la tâche au développeur en lui permettant de se concentrer sur les services fonctionnels de ses composants. Pour être en conformité avec la scalabilité des environnements Cloud, nous utilisons une approche basée sur des micro-conteneurs pour le déploiement de composants. Dans la deuxième contribution, nous étendons le standard OCCI (Open Cloud Computing Interface) pour ajouter dynamiquement des facilités de supervision et de reconfiguration aux ressources Cloud, indépendamment de leurs niveaux de service. Cette extension implique la définition de nouvelles Ressources, Links et Mixins OCCI pour permettre d'ajouter dynamiquement des facilités de supervision et de reconfiguration à n'importe quelle ressource Cloud. Nous étendons par la suite nos deux contributions de supervision et reconfiguration afin d'ajouter des capacités de gestion autonomique aux applications SCA et ressources Cloud. Les solutions que nous proposons sont génériques, granulaires et basées sur les standards de facto (i.e., SCA et OCCI). Dans ce manuscrit de thèse, nous décrivons les détails de nos implémentations ainsi que les expérimentations que nous avons menées pour l'évaluation de nos propositions / Cloud Computing is an emerging paradigm in Information Technologies (IT). One of its major assets is the provisioning of resources based on pay-as-you-go model. Cloud resources are situated in a highly dynamic environment. However, each provisioned resource comes with functional properties and may not offer non functional properties like monitoring, reconfiguration, security, accountability, etc. In such dynamic environment, non functional properties have a critical importance to maintain the service level of resources and to make them respect the contracts between providers and consumers. In our work, we are interested in monitoring, reconfiguration and autonomic management of Cloud resources. Particularly, we put the focus on Service-based applications. Afterwards, we push further our work to treat Cloud resources. Consequently, this thesis contains two major contributions. On the first hand, we extend Service Component Architecture (SCA) in order to add monitoring and reconfiguration requirements description to components. In this context, we propose a list of transformations that dynamically adds monitoring and reconfiguration facilities to components even if they were designed without them. That alleviates the task of the developer and lets him focus just on the business of his components. To be in line with scalability of Cloud environments, we use a micro-container based approach for the deployment of components. On the second hand, we extend Open Cloud Computing Interface standards to dynamically add monitoring and reconfiguration facilities to Cloud resources while remaining agnostic to their level. This extension entails the definition of new Resources, Links and Mixins to dynamically add monitoring and reconfiguration facilities to resources. We extend the two contributions to couple monitoring and reconfiguration in order to add self management capabilities to SCA-based applications and Cloud resource. The solutions that we propose are generic, granular and are based on the de facto standards (i.e., SCA and OCCI). In this thesis manuscript, we give implementation details as well as experiments that we realized to evaluate our proposals
484

Hipotensão pós-exercício resistido em homens hipertensos: influência do uso de captopril / Post-resistance exercise hypotension in hypertensive men: influence of captopril treatment

Queiroz, Andreia Cristiane Carrenho 19 June 2013 (has links)
Uma sessão de exercícios resistidos promove hipotensão pós-exercício em hipertensos (HT). Devido às alterações cardiovasculares impostas pela doença, é possível que os HT apresentem mecanismos hipotensores diferentes dos observados em normotensos (NT). Além disso, os HT utilizam medicamentos anti-hipertensivos que podem afetar as respostas fisiológicas pós-exercício. O objetivo desta tese foi avaliar, em homens HT, o efeito de uma sessão de exercício resistido sobre a pressão arterial (PA) e seus os mecanismos hemodinâmicos e autonômicos, comparando este efeito com o observado em NT e verificando o efeito do uso do captopril sobre estas respostas. Participaram do estudo, 12 HT (50±3anos) e 14 NT (44±3anos). Os hipertensos foram estudados em duas situações: após 4 semanas de placebo ou captopril (3 x 50mg/dia) administrados em formato crossover e de forma duplo-cega. Os NT foram estudados apenas 1 vez sem nenhum medicamento. Em cada grupo/situação experimental os voluntários realizaram 2 sessões experimentais conduzidas em ordem aleatória: Controle (repouso) e Exercício (6 exercícios, 3 séries até a fadiga moderada, 50% de 1RM). As variáveis foram medidas antes e em 2 momentos pós-intervenções: Pós1 (entre 30-80min) e Pós2 (após 7h). Além disso, a PA foi medida por 24h em condições ambulatoriais. No Pós1, a PA sistólica diminuiu de forma similar nos grupos/situações (NT=-8±2; HT não medicado=-13±2; HT medicado=-12±2mmHg). A PA diastólica também diminuiu, mas a queda foi maior nos HT não medicados em comparação com os NT (-9±1 vs. -4±1mmHg, respectivamente) e foi igual nos hipertensos com e sem medicamento. Em cada grupo/situação, a hipotensão pós-exercício se acompanhou de redução do débito cardíaco (DC) em parte dos voluntários e da resistência vascular periférica (RVP) na outra parte. O volume sistólico (VS) diminuiu (NT=-14±5; HT não medicado=-11±5; HT medicado=-17±5ml) e a FC aumentou (NT=+13±3; HT não medicados=+13±2; HT medicados=+13±2bpm) pós-exercício de forma similar nos grupos/situações. Também de forma similar, o balanço simpatovagal cardíaco aumentou (NT=+1,9±0,4; HT não medicados=+1,4±0,3; HT medicados=+1,8±0,3) e a sensibilidade barorreflexa diminuiu (NT=-5±1; HT não medicados=-4±2; HT medicados=+3±1mmHg/bpm) pós-exercício. No Pós2, não houve efeito do exercício sobre nenhuma variável. A PA ambulatorial foi semelhante em todos os grupos/situações. Em conclusão, uma sessão de exercício resistido promove efeito hipotensor no ambiente laboratorial em NT e HT medicados ou não, mas este efeito não se mantém em condições ambulatoriais. Nos HT, a magnitude de queda da PA diastólica é maior que nos NT. Os mecanismos hemodinâmicos e autonômicos da hipotensão pós-exercício são semelhantes em NT e HT medicados ou não. O determinante hemodinâmico (DC ou RVP) da hipotensão pós-exercício varia de um indivíduo para outro, mas a redução da PA se acompanha de redução do VS e aumento da FC, sendo este último resultante do aumento do balanço simpatovagal cardíaco e da redução da SB / A session of resistance exercise promotes post-exercise hypotension in hypertensive subjects (HT). Due to the cardiovascular alterations imposed by the disease, it is possible that HT present hypotensive mechanisms different from those observed in normotensive subjects (NT). Moreover, HT frequently receive antihypertensive medications that might affect post-exercise responses. The aim of this thesis was to evaluate, in HT men, the effects of resistance exercise session on blood pressure (BP) and its hemodynamic and neural mechanisms, comparing these effects with the responses observed in NT and verifying the effect of captopril use on these responses. Twelve HT (50±3 years) and 14 NT (44±3 years) participated in the study. HT were studied in two situations, after 4 weeks of placebo and captopril (3 x 50mg/day) administered in a crossover double-blind design. NT was studied only once without any medication. At each group/situation, subjects underwent 2 experimental sessions performed in a random order: Control (rest) and Exercise (6 resistance exercises, 3 sets until moderated fatigue, 50% of 1RM). Measurements were taken before and in 2 post-intervention moments (Post1 - between 30-80min and Post2 - after 7pm). Moreover, ambulatory BP was measured after the sessions. In Post1, systolic BP decreased similarly in all groups/situations (NT=-8±2; unmedicated HT=-13±2; medicated HT=-12±2mmHg). Diastolic BP also decreased, but this decrease was greater in unmedicated HT compared with NT (-9±1 vs. -4±1mmHg, respectively), and were similar in HT with and without medication. Regardless of group/situation, exercise promoted a decrease in cardiac output (CO) in some subjects and a reduction in systemic vascular resistance (SVR) in others. Stroke volume (SV) decreased (NT=-14±5; unmedicated HT=-11±5; medicated HT=-17±5ml) and HR increased (NT=13±3; unmedicated HT=13±2; medicated HT=13±2bpm) after exercise similarly in all groups/situations. Also similarly between groups/situations, cardiac sympathovagal balance increased (NT=+1,9±0,4, unmedicated HT=+1.4±0.3, medicated HT=+1,8±0,3) and BS decreased (NT=-5±1; unmedicated HT=-4±2; medicated HT=+3±1mmHg/bpm) post-exercise. In Post2, in all groups/situations, exercise did not affect any variable. In addition, ambulatory BP was similar after the control and exercise sessions in all group/situation. In conclusion, a single bout of resistance exercise session promotes post-exercise hypotension in the laboratory in NT and HT subjects receiving or not captopril, but this hypotensive effect is not maintained under ambulatory conditions. The magnitude of BP decrease is greater in non-medicated HT than in NT, and it was not changed by captopril. Autonomic and hemodynamic mechanisms of post-exercise hypotension are similar in NT and HT receiving medication or not. The hemodynamic determinant (CO or SVR) of post-exercise hypotension varies from one subject to another. However, BP reduction is accompanied by decrease in SV and an increase in HR that results from an increase in cardiac sympathovagal balance and decrease in BS
485

Caracterização da modulação autonômica cardiovascular nas posições supina e vertical, usando-se a manobra postural passiva, em pacientes com história clínica de síncope neurocardiogênica e indivíduos saudáveis / Characterization of autonomic cardiovascular modulation in the supine and vertical positions, using the passive postural maneuver, in patients with a history of neurocardiogenic syncope and healthy individuals

Leite, Mariana Adami 28 August 2017 (has links)
A síncope neurocardiogênica (SINC) é causada por redução global e aguda do fluxo sanguíneo cerebral, subsequente à hipotensão arterial, com perda transitória da consciência e do tônus postural. Entretanto, existem divergências, quanto às repostas das variáveis cardiovasculares que antecedem o início da SINC, provocada pelo seu principal teste diagnóstico, a manobra postural passiva (MPP) ou Tilt-test. Recentemente, a possibilidade de analisar as variáveis cardiovasculares, com métodos computacionais não-invasivos, lineares (ML) e não lineares (MNL) tem permitido o estudo das entropias, da variabilidade da frequência cardíaca (VFC), da pressão arterial sistólica (VPAS) e da sensibilidade barorreflexa (SBR); estudos preliminares sugerem que a SINC poderia estar relacionada ao desequilíbrio da modulação autonômica dessas variáveis. Objetivo: usar métodos computacionais, ML e MNL, na análise da VFC, e ML na análise da VPAS e da SBR, em pacientes com história clínica de SINC, com resposta positiva ou negativa à MPP, e em indivíduos saudáveis. Métodos: Foram estudados 51 indivíduos, divididos em 3 grupos, sendo 16 positivos, 18 negativos e 17 saudáveis. Os ML usam algoritmos nos domínios do tempo (DT) e da frequência (DF) (Transformada rápida de Fourier), e os MNL usam alogarítmos da entropia amostral (SampEn) m=2 e r= 20%. Foram analisados 2 momentos: Pré-Tilt (posição supina; trechos com 1000-1500 pontos) e Tilt pré-síncope (70º de inclinação; trechos com 1000-1500 pontos; anteriores à síncope), sendo estudados os mesmos momentos para o grupo controle. Resultados: Não foram encontradas diferenças estatísticas entre os grupos TTP, TTN e Controle para os parâmetros: Idade (anos), Peso (kg), Altura (m) e IMC (kg/m2), pressão arterial sistólica (PAS), pressão arterial diastólica (PAD), frequência cardíaca (FC) e frequência respiratória. Na análise VFC por meio de ML no DT e DF, no momento Pré-Tilt e Tilt pré-síncope, não foi encontrada diferenças estatísticas 8 entre os grupos TTP, TTN e Controle para os parâmetros Mean-iRR(ms), SDiRR(ms), RMSSD(ms), LF(un) (ms2), HF(un) (ms2) e LF/HF. Comparando-se os momentos Pré-Tilt vs Tilt nos grupos TTP, TTN e Controle (análise intra-grupo) observamos diferenças significantes para as variáveis: Mean-iRR(ms), SD-iRR(ms), RMSSD(ms), LF(un), HF(un) (ms2) e LF/HF. Houve na análise da VFC por MNL (SampEn) no grupo Controle, redução significativa dos valores entre as fases Pré-Tilt vs Tilt (2,19 ± 0,40 vs 1,68 ± 0,50, p = 0,001). Houve em ambos os grupos (TTP, TTN e Controle) aumento significativo do LF-PAS, quando comparamos as fases Pré-Tilt vs Tilt (TTP: 6,72 ± 5,67 vs 13,03 ± 10,759 mmHg2, p = 0,001; TTN: 7,25 ± 4,22 vs 13,42 ± 8,62 mmHg2, p = 0,013; Controle: 5,99 ± 2,20 vs 23,07 ± 6,26 mmHg2, p < 0,0001). Além disso, evidenciaram-se maiores valores, estatisticamente significantes, quando comparamos os grupos Controle vs TTP no momento Tilt (23,07 ± 6,26 vs 13,03 ± 10,59 mmHg2, p < 0,001) e Controle vs TTN no momento Tilt (23,07 ± 6,26 vs 13,42 ± 8,62 mmHg2, p < 0,001). Houve em todos os grupos redução significativa da SBR, quando comparamos as fases Pré-Tilt vs Tilt (TTP: 30,22 ± 15,67 vs 13,16 ± 6,08 ms/mmHg, p < 0,0001; TTN: 22,98 ± 11,23 vs 11,55 ± 3,34 ms/mmHg, p < 0,0001; e Controle: 26,75 ± 6,94 vs 12,25 ± 3,88 ms/mmHg, p < 0,0001). Além disso, no grupo TTP e Controle, houve redução significativa dos valores do índice de efetividade barorreflexa (BEI) entre as fases Pré-Tilt vs Tilt (0,50 ± 0,15 vs 0,40 ± 0,13, p = 0,033) e (0,54 ± 0,07 vs 0,46 ± 0,16, p =0, 030) respectivamente. Conclusões: os achados do presente estudo permitiram as seguintes conclusões: 1- a VFC, com métodos lineares (domínios do tempo e frequência) e não lineares (Entropia Amostral), bem como a VPAS (domínios do tempo e da frequência) e a SBR não documentaram nas fases Pré-Tilt e Tilt pré- síncope (fase de estabilidade das variáveis, após a mudança postural até momento anterior ao aparecimento dos pródromos ou da síncope), diferenças estatísticas entre os 2 grupos de pacientes adultos e com história altamente sugestiva de SINC, como doença isolada, com Tilt-test positivo e negativo; 2- o grupo Controle saudável somente foi diferente dos grupos TTP e TTN no parâmetro LF da VPAS; a importância fisiológica desse achado é de difícil explicação, porque não existem na 9 literatura, para esse parâmetro, valores normais da média e dos intervalos de confiança. / Neurocardiogenic syncope (SYN) is caused by a global and acute reduction of cerebral blood flow, subsequent to hypotension, with transient loss of consciousness and postural tone. However, there are differences in the responses of the cardiovascular variables that precede the beginning of the SYN, caused by its main diagnostic test, the passive postural maneuver (PPM) or Tilt-test. Recently, the possibility of analyzing cardiovascular variables using non-invasive, linear (ML) and non-linear (MNL) computational methods has allowed the study of entropies, heart rate variability (HRV), systolic blood pressure variability (VPAS) and baroreflex sensitivity (SBR). Preliminary studies suggest that the SYN could be related to the imbalance of the autonomic modulation of these variables. Objective: To use computer methods, ML and MNL, in the analysis of HRV, and ML in the analysis of VPAS and SBR, in patients with a clinical history of SYN, with positive or negative response to PPM, and in healthy individuals. Methods: Fifty-one individuals were studied, divided into three groups: 16 positive, 18 negative and 17 healthy. MLs use algorithms in the time (DT) and frequency (DF) (Fast Fourier Transform) algorithms, and MNLs use sample entropy m (2) and r = 20%. Two moments were analyzed: Pre-Tilt (supine position, recording 1000-1500 points) and pre-syncope Tilt (70º inclination, recording 1000-1500 points, prior to syncope), being studied the same moments for the control group. Results: There were no statistical differences between the TTP, TTN and Control groups for the parameters: Age (years), Weight (kg), Height (m) and BMI (kg / m2), systolic blood pressure Diastolic (DBP), heart rate (HR) and respiratory rate. No statistical differences were found between the TTP, TTN and Control groups (in the Pre-Tilt and Tilt) for the Mean-iRR (ms), SD-iRR (ms), RMSSD (ms), LF (un) (ms2), HF (un) (ms2) and LF / HF. Comparing the Pre-Tilt vs Tilt moments in the TTP, TTN and Control groups (intra-group analysis) we observed significant differences for the variables: Mean-iRR (ms), SD-iRR (ms), RMSSD (ms), 11 LF (Un), HF (un) (ms2) and LF / HF. There was a significant reduction in the values between the Pre-Tilt vs Tilt phases (2.19 ± 0.40 vs 1.68 ± 0.50, p = 0.001) in the analysis of HRV by MNL (SampEn) in the Control group. There was a significant increase in LF-PAS in both groups (TTP, TTN and Control) when we compared the Pre-Tilt vs Tilt phases (TTP: 6.72 ± 5.67 vs 13.03 ± 10.759 mmHg2, p = 0.001; TTN: 7.25 ± 4.22 vs 13.42 ± 8.62 mmHg2, p = 0.013; Control: 5.99 ± 2.20 vs. 23.07 ± 6.26 mmHg2, p <0.0001). In addition, statistically significant higher values were found when we compared the Control vs TTP groups at the time of Tilt (23.07 ± 6.26 vs 13.03 ± 10.59 mmHg2, p <0.001) and Control vs. TTN at the time of Tilt (23.07 ± 6.26 vs 13.42 ± 8.62 mmHg2, p <0.001). There was a significant reduction of SBR in all groups when comparing the Pre-Tilt vs Tilt phases (TTP: 30.22 ± 15.67 vs. 13.16 ± 6.08 ms / mmHg, p <0.0001; P <0.0001, and control: 26.75 ± 6.94 vs 12.25 ± 3.88 ms / mmHg, p <0, 0001). In addition, in the TTP and Control group, there was a significant reduction in baroreflex effectiveness index (EIB) between the Pre-Tilt vs. Tilt phases (0.50 ± 0.15 vs. 0.40 ± 0.13, p = 0.033) and (0.54 ± 0.07 vs 0.46 ± 0.16, p = 0.030) respectively. Conclusions: The findings of the present study allowed the following conclusions: 1 - HRV, with linear methods (time and frequency domains) and nonlinear (Entropy Amostral), as well as VPAS (time domain and frequency domain) and SBR did not document Pre-Tilt and Tilt phases pre-syncope (Stability of variables, after postural change until the time before prodrome or syncope appeared), statistical differences between the 2 groups of adult patients and with a highly suggestive history of SYN, As isolated disease, with positive and negative Tilt-test; 2- the Healthy control group was only different from the TTP and TTN groups in the LF parameter of the VPAS; The physiological importance of this finding is difficult to explain because there are no normal values of the mean and confidence intervals in the literature for this parameter.
486

Neuromodulation des douleurs par l'entraînement dans les douleurs diffuses / Neuromodulation of pain by training in diffuse pain

Bonnabesse Le Fur, AnaÏs 12 February 2019 (has links)
La fibromyalgie (FM) touche 1,4 à 2,2 % de la population générale avec une nette prédominance féminine (80 % des sujets). Ce syndrome est caractérisé par des douleurs chroniques diffuses, des troubles du sommeil, des troubles cognitifs, des perturbations émotionnelles et une fatigue chronique. Les mécanismes physiopathologiques de la FM ne sont pas complètement élucidés. Cependant, la FM est considérée comme un syndrome lié au stress. Des déséquilibres du système nerveux autonome (SNA) et de l'axe hypothalamo-hypophyso-surrénalien (HHS) ont été mis en évidence dans la FM. Ce déficit de l’axe du stress (SNA et HHS) induirait secondairement des dysfonctionnements des contrôles endogènes de la douleur. A partir de cette hypothèse et en s’appuyant sur deux essais cliniques, notre objectif est d’évaluer l'efficacité d'un programme d’entraînement spécifique, sur les douleurs et les symptômes des patientes FM. Une première étude observationnelle de cinq ans, démontre qu’une prise en charge globale, associée à un entraînement physique spécifique [3 sessions de 45 minutes par semaine d’entraînement continue à intensité modérée (MICT), progressivement couplé à un entraînement fractionné à haute intensité (HIIT)] améliore considérablement les symptômes de la FM. Les premiers résultats d'une seconde étude, contrôlée et randomisée de 24 mois, confirment des dysfonctionnements des mécanismes de modulation centrale de la douleur, ainsi qu’un déficit de la régulation autonome, chez au moins une fraction des patientes FM. Ce programme d’entraînement spécifique, encadré et individualisé, dont l’intensité des exercices est définie pour rééquilibrer la balance neurovégétative (tonus parasympathique et réactivité sympathique), permettrait via des mécanismes de neuroplasticité centrale, associés aux effets périphériques tels que l'augmentation de la perfusion vasculaire au niveau musculaire, de soigner la fibromyalgie. / Fibromyalgia affects 1.4–2.2% of the general population, predominately women (more than 80% of subjects). This syndrome is characterised by chronic widespread pain, sleep disturbances, cognitive dysfunction, emotional disorders and chronic fatigue.Physiopathological mechanisms of FM are not fully elucidated but FM is considered a stress related syndrome. Studies on the stress axis in FM have demonstrated dysfunction of both the Autonomic Nervous System (ANS) and the Hypothalamic-Pituitary-Adrenal (HPA) axis. This stress axis deficit (ANS and HPA) could consequently induce dysregulation of pain modulation. According to this hypothesis and using two clinical trials, our main objective is to assess the efficacy of a specific training program on pain and symptoms in female fibromyalgia patients.Firstly, a 5-year observational study shows that overall care coupled with specific physical training [3 sessions of 45 minutes per week of Moderate Intensity Continuous Training (MICT) gradually associated with High Intensity Interval Training (HIIT)] may lead to dramatic improvement of FM symptoms. Secondly, the initial results of a 24-month, controlled, randomised trial (RCT) confirm dysregulation of central pain modulation and a deficit of the autonomic balance, at least in a percentage of FM patients. This specific, supervised, individualised training program with exercise intensity defined to rebalance the neurovegetative system (parasympathetic tone and sympathetic reactivity), associated by peripheric effects as the improvement of muscle perfusion, may allow FM to be treated through central neuroplasticity.
487

Disturbances of autonomic functions in spinal cord injury: autonomic dysreflexia and thermoregulation

Kalincik, Tomas, Medical Sciences, Faculty of Medicine, UNSW January 2009 (has links)
Disorders of the autonomic nervous system constitute serious complications of spinal cord injury (SCI) and their treatment is usually highly prioritised by spinal patients. Among these, autonomic dysreflexia and impaired thermoregulation are potentially life threatening conditions and require effective management. Olfactory ensheathing cells (OECs), progenitor cells and polymeric scaffolds have been tested in animal models of SCI and some of them have been considered for clinical trials. However, evaluation of the effect of such interventions on autonomic functions has received only rudimentary attention and would require a more thorough experimental assessment before the methods are utilised in human patients. This thesis tested two potential therapeutic strategies for autonomic dysreflexia and examined disorders of thermoregulatory functions in a rat model of spinal cord transection. Magnitude and duration of autonomic dysreflexia were evaluated with radio telemetry in spinalised animals treated with (i) implants of OECs and olfactory neurosphere-derived cells seeded in poly(lactic co glycolic) porous scaffolds or with (ii) transplants of OECs alone. (iii) Effects of SCI and of OECs on the morphology of sympathetic preganglionic neurons (SPNs; which are involved in pathogenesis of autonomic dysreflexia) stained for NADPH diaphorase were examined. (iv) Doppler ultrasonography and infrared thermography were used to assess responses of tail blood flow and surface temperature to cold. Transplants of OECs alone, but not in combination with olfactory neurosphere-derived cells and polymeric scaffolds, resulted in significantly shortened episodes of autonomic dysreflexia. This may be attributed to the alterations to the morphology of SPNs adjacent to the lesion: a transient increase in the morphometric features of the SPNs was evoked by spinal cord transection and this was further altered by transplantation of OECs. The thesis also showed that local responses of tail blood flow and temperature to cold were not abolished by complete SCI suggesting that temperature homeostasis could still be maintained in response to cold. It is hypothesised that OECs facilitate improved recovery from autonomic dysreflexia through alteration of the morphology of SPNs. Furthermore, it is suggested that the role of the tail in heat conservation can be regulated by mechanisms that are independent of the descendent neural control from supraspinal centres.
488

An autonomic communication framework for wireless sensor networks

Sun, Jingbo January 2009 (has links)
Sensor networks use a group of collaborating sensor nodes to collect information about real world phenomena. Sensor nodes use low-power short-range radio links to communicate with each other. Communication between sensor nodes shows significant variation over time and space. This can lead to unreliable and unpredictable network performance. These dynamic and lossy characteristics of wireless links pose major challenges for building reliable sensor networks and raise new issues that data delivery protocols must address. This thesis addresses the problems of designing protocols to overcome time-varying environmental conditions that lead to unpredictable network performance. The goal is to provide reliable data delivery in sensor networks and to minimise energy use. The major contributions of this thesis are: measuring the performance of wireless links in field trials on a time scale of weeks; systematic analysis of strengths and weaknesses of existing data delivery protocols; and the design, implementation and testing of a novel autonomic communication framework. We have measured link quality over time in experiments in unattended outdoor environments. Most previous work focused on spatial properties and experiments were not extensive, only lasting for a few hours. Besides common phenomena found in other work, such as the variation of network performance over time and the existence of asymmetric links, we find that links are independent over long time scales, and performance patterns of links are different. We also analyse the performance of data delivery protocols that use different techniques to improve reliability in sensor networks. Through systematic analysis of strengths and weaknesses of existing data delivery strategies, we find that networks using a single technique can only perform well for a limited range of link conditions. Different strategies are required in different operating conditions. Based on these experimental and theoretical studies, a novel autonomic communication framework (ACF) for wireless sensor networks is proposed. Nodes in this ACF are able to change their behaviour to adapt to time-varying environments so that optimal network performance can be achieved. Our framework provides a holistic solution for reliable data delivery to overcome time-varying wireless links. Our implementation and experimental evaluations demonstrate that this holistic framework is effective for reliable and energy-efficient data delivery in realistic sensor network settings.
489

Psychophysiological reactions to experimental stress : relations to pain sensitivity, position sense and stress perception

Heiden, Marina January 2006 (has links)
Stress and monotonous work contribute substantially to the development of chronic musculoskeletal disorders. Yet, the pathophysiological mechanisms underlying the process, particularly the involvement of autonomic regulation, remain unclear. It has been suggested that altered motor control resulting from distorted sensory information from fatigued muscles may be an important component in the development of musculoskeletal disorders. Animal studies have shown that sympathetic nervous system activation exerts actions in skeletal muscles, such as vasoconstriction and modulation of afferent information from muscle spindles. However, few attempts have been made to address this issue in humans. Therefore, the first aim of the thesis was to investigate the impact of repetitive computer work with and without additional stressors on muscle oxygenation and position sense in the upper extremity. Assuming an important role of stress in the development of chronic musculoskeletal symptoms, one may expect open or latent manifestations of such symptoms in patients with non-specific stress-related illnesses. It is possible that sympathetic activation may influence pain perception, and that treatments aimed at reducing stress may also affect the pain experience. Thus, the second aim of the thesis was to evaluate the effects of a cognitive-behavioral training program and a physical activity program for patients with stress-related illnesses on autonomic reactivity, pain, and perceived health. First, a laboratory model of computer mouse use was characterized in terms of biomechanical exposure of the wrist, and wrist position sense was determined before and after 45 minutes of continuous mouse use. Then, the effects of performing the computer mouse work under time pressure and precision demands were determined. Autonomic activity and muscle oxygenation in the upper extremity were measured during the work, and wrist position sense was assessed before and after the work. When patients with stress-related illnesses were compared to healthy individuals in autonomic reactivity to functional tests, pressure-pain thresholds, and ratings of health, indications of a relation between autonomic reactivity and symptoms of pain was found. Hence, in a subsequent evaluation of a cognitive-behavioral training program and a physical activity program for patients with stress-related illnesses, post intervention effects on autonomic reactivity to functional tests, pressure-pain thresholds, ratings of health and return-to-work were studied during a period of 12 months after the intervention. The main findings were the following. 1) Wrist kinetics data obtained during the computer mouse work showed similarities to previously presented data for mouse-operated design tasks. 2) When time pressure and precision demands were added to the computer work, increased autonomic activity paralleled with decreased muscle oxygenation in the upper extremity was found. Wrist position sense accuracy, however, did not decrease after the work as it did when the work was performed without the additional demands. The result is intriguing, as it does not appear to be in concordance with previous animal studies. 3) Patients with stress-related illnesses showed higher autonomic reactivity to cognitive and physical laboratory tests than healthy control subjects. They also had substantially lower pressure-pain thresholds in the back, and rated poorer health and health-related behavior than the control subjects. 4) We found little difference in effect of cognitive-behavioral training and physical activity, compared to usual care, for patients with stress-related illnesses. Patients in the control group showed an improvement of about the same magnitude as in the treatment groups over the 12-month follow-up period. The present findings indicate a non-additive relation between autonomic activity during repetitive work and position sense inaccuracy. Furthermore, patients with stress-related illnesses often reported pain in the neck, shoulders, and lower back. This was associated with lower pressure-pain thresholds in the back and a modest increase in sympathetic reactivity to physical and mental tests, which might suggest a potential use of these methods in the clinical examination and rehabilitation of patients with stress-related illnesses.
490

A System for Using Perceiver Input to Vary the Quality of Generative Multimedia Performances

Jeff, Byron A. 15 September 2005 (has links)
Generative Multimedia (GM) applications are an increasingly popular way to implement interactive media performances. Our contributions include creating a metric for evaluating Generative Multimedia performances, designing a model for accepting perceiver preferences, and using those preferences to adapt GM performances. The metric used is imprecision, which is the ratio of the actual computation time of a GM element to the computation time of a complete version of that GM element. By taking a perceiver's preferences into account when making adaptation decisions, applications can produce GM performances that meet soft real-time and resource constraints while allocating imprecision to the GM elements the perceiver least cares about. Compared to other approaches, perceiver-directed imprecision best allocates impreciseness while minimizing delay.

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