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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.
101

Vridningsmekanism för Stigortsborrmaskin / Tilt Mechanism for a Raiseboring machine

Stenhammar, Philip January 2020 (has links)
Examensarbetet är utfört tillammans med Epiroc genom Svea Teknik AB och som skett inom mastersprogrammet Maskinkonstruktion på KTH.  Stigortsborrmaskiner används inom gruvindustrin till att exempelvis borra hisschakt, malmpassager eller dränering mellan två redan existerande orter. Epiroc har tagit fram en stigortsborrmaskin, Robbins 73RH, som kan borra ner till 700 m med metoden uppåtgående stigfullsborrning genom en hydraulisk drivenhet som placeras bredvid stigortsborrmaskinen.  Robbins 73RH transporteras liggandes på en tillhörande crawler, med modellnamn T190D, för att reducera den krävda takhöjden vid transport. Väl på plats för att borra lastas Robbins 73RH av crawlern till sitt vertikala upprätta läge genom att stigortsborrmaskinen vrids 90° med en vridningsmekanism monterad mellan stigortsborrmaskinen och crawlern. Dagens lösning involverar tidskrävande manuellt arbete för operatörerna vilket resulterar i tunga lyft och risk för klämskador när vridningsmekansimen ska kopplas från eller till stigortsborrmaskinen. Syftet med detta examensarbete är att utveckla ett nytt koncept som reducerar tiden för på- och avlastning samt är säkrare för operatörerna. Detta utfördes genom att ta fram en kraftmodell, generera koncept som evaluerades med en Pugh’s matris och vidareutveckla ett valt koncept utifrån de givna kraven. Det nya konceptet kopplas från och till stigortsborrmaskinen med hjälp av en hydrauliskt styrd axel vilket resulterar i förbättrad säkerhet och reducerad tid för på- och avlastning. Antalet tunga lyft för operatörerna har även reduceras vilket resulterar i en förbättradarbetsmiljö där även risken för klämskador har begränsats. / This Master Thesis has been carried out together with Epiroc through Svea Teknik AB and has been done within the Master’s program Machine Design at KTH. Raisebroing machines are used in the mining industry for example drilling elevator shafts, ore passages or drainage between two already existing mine shafts. Epiroc has developed a raiseboring machine called Robbins 73RH that can drill down to 700 m using the upward reaming method with hydraulics which is provided by a drive unit. Robbins 73RH is transported lying down at a associated crawler, called T190D, in order to reduce the required roof height. Once in place to drill, Robbins 73RH is unloaded from the crawler to its upright vertical position by rotating it 90° with a tilt mechanism fitted between the raiseboring machine and crawler. Today’s solution involves time consuming manual labor for the operators which results in heavy lifts and risk for crushing when the tilt mechanism needs to be taken on or off the raiseboring machine. The purpose of this Master Thesis is to design a new concept that reduces the time for connecting on and off the raiseboring machine and that also is safer to operate. This is performed by designing a force analysis, generate concepts that are evaluated with Pugh’s matrix and last develop a concept that the supervisors at Epiroc has chosen. The new concept connects to the raiseboring machine using a hydraulic driven shaft which results in improved safety and reduced time when loaded on or off the crawler. The Amount of heavy lifts has been reduced which results in an improved working environment where the risk of crushing no longer arises to the same extent as for the original solution.
102

A Provacative Test to Determine Brain Compliance in the Management of Patients with Hydrocephalus

Manwaring, Preston K. 18 November 2005 (has links) (PDF)
Non-invasive techniques to explore intracranial compliance and pressure have been extensively explored in recent years. Previous techniques have used expensive technologies to make these measurements, often with difficulty. We present a novel, inexpensive provocative test to observe trends in intracranial compliance measurement targeted towards the treatment and management of hydrocephalus. Two techniques are proposed which derive data from the digital and supraorbital arteries as well as tympanic membrane displacement. This requires the use of two photo-plethysmographic sensors and a TMD sensor. A common tilt table apparatus is used to methodically and artificially increase intracranial pressure to stress the cranial system during the test. The results from this test are computed using a digital signal processing algorithm to determine phase difference between the waveforms. Further research is also proposed.
103

Broadening the Reading Experience on Mobile Devices using Tilt-based Input : An Explorative Design Study / Att Bredda Läsupplevelsen på Mobiltelefoner genom Gyroskopiska Interaktioner : En Utforskande Designstudie

Ahlström, Marcus January 2018 (has links)
This thesis is an explorative study aimed at the possibility of integrating tilt-based input to improve the reading experience on smartphones. Previous works from the early 2000s have been skeptical towards tilt-based navigation, deeming it unruly and imprecise. To investigate if today’s technology has unlocked new possibilities; two experimental reading methods were designed, created and tested iteratively on 20, respectively 18 participants. The first method is a reassessment of tilt-based auto-scrolling and the second is a novel approach comparable to tilt-based paging. Data from the reading sessions were collected quantitatively in tandem with qualitative data from post-session interviews. The results indicate good potential and a reading performance similar to the standard navigation method. The importance of accommodating people with different reading behaviours was also discussed. / Detta examensarbete utforskar om gyroskopiska interaktioner kan användas för att förbättra läsupplevelsen på mobiltelefoner. Tidigare forskning från det tidiga 2000-talet har varit skeptiska mot gyroskopisk navigation, på grund av dålig precision och stabilitet. För att utforska om dagens teknologi har öppnat nya möjligheter; skapades, designades och testades två experimentella läsmetoder på 20 respektive 18 deltagare. Den första metoden är en återkoppling till tidigare forskning medans den andra utforskar ett nytt sätt som liknar gyroskopisk sidindelning. Data från läs sessionerna samlades i både kvantitativ och kvalitativ form, varav den senare med semistrukturerade intervjuer. Resultaten indikerar god potential och en läsprestanda som liknar den standardiserade läsmetoden. Vikten av att tillgodose människors individuella läsningsbeteende blev också diskuterat.
104

Position, Attitude, and Fault-Tolerant Control of Tilting-Rotor Quadcopter

Kumar, Rumit 16 June 2017 (has links)
No description available.
105

A Look at the Optimum Slope of a Fixed Solar Panel for Maximum Energy Collection for a One Year Time Frame

Alhaidari, Salah January 2017 (has links)
No description available.
106

The Characterization of Pulse Front Tilt and Spatial Dispersion in 800 NM Femtosecond Lasers

Doyle, Benjamin A. L. January 2005 (has links)
<p> This thesis presents a study of diagnostics of pulsed laser systems. Two simple and cost effective devices are constructed that measure common spatio-temporal distortions. The first is a spectrally-resolved knife-edge (SRKE) for spatially and spectrally resolving a laser beam, which enables spatio-temporal distortions to be measured. The second is an interferometric autocorrelation taken with a 2-photon diode. A lens is used to focus light from the entire cross section of the beam onto the diode. By scanning the diode through the focus, the effects of pulse-front-tilt on focused beam pulse durations can be measured. These techniques are compared with current theoretical models, and with each other, to establish their reliability and practicality, as well as the reliability of the commercial techniques. SRKE is found to be highly sensitive to spatial and angular dispersion, and also able to measure the frequency gradient, although not as precisely. Interferometric autocorrelation is only able to resolve effects on duration. It can detect the presence of significant spatio-temporal distortion, but several scans must be taken as a function of distance from the lens, through the focus.</p> <p> A commercially built GRENOUILLE was also tested on pulses compressed with a hollow-capillary-prism pulse compressor. Compression of 800 nm, 50 fs pulses to less than 19 fs was achieved with an overall transmission efficiency of 33%. With further work, efficiency could be increased, and pulse duration decreased.</p> / Thesis / Master of Science (MSc)
107

Optimum positioning for anteroposterior pelvis radiography: A literature review

Alzyoud, K., Hogg, P., Snaith, Beverly, Flintham, K., England, A. 15 May 2018 (has links)
Yes / Pelvic radiography is used for the identification of hip joint changes, including pathologies such as osteoarthritis. Several studies have recommended that the position for this radiological procedure should be standing, not supine, to reflect the functional appearances of the hip joint. The aim of this review was to evaluate pelvis radiography positioning with respect to the image appearances and information provided for clinical decision-making. Aside from this, potential recommendations to the radiographic technique for an erect pelvis projection will be considered. Method: A literature search was performed using databases/ systems (ScienceDirect, Web of Science, PubMed, and MEDLINE). Only articles written in English were included. Results: Twenty-five articles were identified. Findings from the review describe the effect of repositioning from supine to erect on a series of specific hip measurements. These include pelvic tilt, joint space width, and the acetabular component. Conclusion: Evidence within the literature illustrates that in several studies, there were differences when repositioning from supine to standing for a number of pelvic metrics. Standing positioning is promoted by some authors since this may facilitate the early diagnosis of hip joint pathology and assist in the planning of surgical interventions. Literature is very limited on how to optimally perform erect pelvis radiography, and this should be an area for future research.
108

Estudo das características antropométricas e das respostas de frequência cardíaca e pressão arterial, e suas respectivas variabilidades, à manobra postural passiva em pacientes com suspeita clínica de síncope neurocardiogênica / Study of anthropometric characteristics and responses of heart rate and blood pressure, and their variability, induced by passive postural maneuver in patients with clinically suspected neurocardiogenic syncope.

Leite, Mariana Adami 03 October 2013 (has links)
A síncope neurocardiogênica (SNC) é caracterizada por perda transitória da consciência e do controle postural, devido a uma hipoperfusão cerebral global de surgimento abrupto, com recuperação rápida e espontânea do paciente ao retornar à posição horizontal. Entretanto, investigações adicionais são necessárias para melhor avaliação das respostas cardiorrespiratórias e autonômicas de pacientes com SNC submetidos ao Tilt-test. O presente estudo teve como objetivo avaliar, em pacientes com história clínica sugestiva de SNC, os efeitos da mudança postural induzidas pelo Tilt-test na pressão arterial (PA) e frequência cardíaca (FC), na variabilidade cardiocirculatória e na sensibilidade barorreflexa (SBR). Além disso, o estudo também avaliou a relação entre a idade, sexo e características antropométricas dos pacientes com as respostas ao Tilt-test, e a relação entre o tempo do início da mudança postural e o momento da síncope, com um ou mais parâmetros acima mencionados. O estudo foi dividido em 3 partes: 1 Estudo retrospectivo de 180 pacientes, com história clínica sugestiva de SNC, mas que apresentaram Tilt-test positivo (TTP) (128 indivíduos) ou negativo (TTN) (52 indivíduos) para síncope; 2 Estudo da variabilidade da frequência cardíaca (VFC), usando-se métodos lineares (Transformada Rápida de Fourier) em pacientes com história clínica sugestiva de SNC, e com respostas positiva ou negativa ao Tilt-test. Foram incluídos 62 pacientes, 31 com Tilt-test positivo e 31 negativo; 3 Estudo da variabilidade da pressão arterial sistólica (VPAS), usando-se métodos lineares (Transformada Rápida de Fourier), e da SBR (Método da Sequência) em pacientes com história clínica sugestiva de SNC, e com respostas positiva ou negativa ao Tilt-test. Foram estudados 33 indivíduos, 16 com Tilt-test positivo e 17 negativo. Estudo 1 Observou-se que a incidência de SNC foi 1,5 vezes maior em mulheres do que em homens. Além disso, os grupos TTP e TTN apresentaram idade e características antropométricas semelhantes entre si, e não houve significância estatística nas correlações entre o tempo do início da posição vertical até a síncope, a idade e as características antropométricas. Estudo 2 Comparando os 2 grupos nos domínios do tempo (SD-iRR, variância-iRR, RMSSD) e da frequência (LF (un), HF (un) e LF/HF) nas fases Pré-Tilt, Tilt e Pós-Tilt, com exceção do iRR (ms), não observou-se diferença entre os grupos. Houve, na fase Tilt, um menor valor do iRR no grupo TTP. O Pré-Tilt comparado ao Tilt, promoveu em ambos os grupos redução do iRR e aumento na razão LF/HF. Estudo 3 Comparando-se os grupos TTP e TTN no Pré-Tilt e Tilt, não houve diferença no LF da PAS e na SBR. O Tilt promoveu, em ambos os grupos, aumento no LF da PAS, redução na SBR. Somente no grupo TTP foi observado aumento no desvio padrão da PAS durante o Tilt. Em conclusão, o estudo 1 demonstrou que a SNC não foi influenciada pela idade e características antropométricas, no que diz respeito à prevalência, e ao tempo de duração entre o início da mudança postural no Tilt-test e o momento do aparecimento da síncope na posição vertical. O estudo 2 demonstrou que indivíduos com suspeita clínica de SNC, e Tilt-test positivo ou negativo não apresentam anormalidades no balanço simpato-vagal cardíaco, mas, apresentaram diferenças no iRR. O estudo 3 não evidenciou diferenças no controle autonômico cardiovascular (LF-PAS e SBR) entre os grupos TTP e TTN no Pré-Tilt e Tilt. Os estudos 2 e 3 mostraram que com a metodologia utilizada na análise da VFC e VPAS não foi possível detectar anormalidades significativas da modulação autonômica cardiovascular nos grupos TTP e TTN, e desse modo, prever na posição vertical do Tilttest, se um paciente com história clínica sugestiva de SNC apresentará ou não síncope. / Neurocardiogenic syncope (NCS) is characterized by transient loss of consciousness and postural control, due to abrupt global cerebral hypoperfusion, with rapid and spontaneous recovery after changing the patient to horizontal position. However, further investigations are necessary to better understand the cardiorespiratory and autonomic responses to the Tilt-test in NCS patients. The present study aimed to evaluate, in patients with a history suspicion of NCS, the effects of postural change (Tilt-test) on blood pressure (BP) and heart rate (HR), on the cardiovascular variability and baroreflex sensitivity (BRS). Furthermore, the study also assessed the relationship between age, sex and anthropometric characteristics with the Tilt-test responses, and the relationship between the time period taken to experience syncope following postural change and the above cited parameters. The study was divided into three parts: 1 A retrospective study with 180 patients with a history suspicion of NCS, that experienced (TTP; 128 individuals) or not (TTN; 52 individuals) syncope following Tilt-test; 2 A study of the heart rate variability (HRV), assessed by linear methods (Fast Fourier Transform), in patients with a history suspicion of NCS and that experienced, or not, syncope following Tilt-test. The study included 62 patients (31 in TTP group and 31 in TTN group); 3 A study of the systolic blood pressure variability (SAPV), using linear methods (Fast Fourier Transform), and of the BRS (Sequence Method) in patients with a history compatible with NCS and that experienced, or not, syncope following Tilt-test. The study included 33 patients (16 in TTP group and 17 in TTN group). Study 1 it was observed that the incidence of NCS was 1.5 times greater in women than in men. Furthermore, groups TTP and TTN showed age and anthropometric characteristics similar to each other and no statistical significance was observed in the correlations among the time period taken to experience syncope following postural change and age and anthropometric characteristics. Study 2 The analysis of the cardiovascular variability, by means of time (SD-iRR, variance-iRR, RMSSD) and frequency (LF (nu), HF (nu) and LF/HF) domain methods, revealed no differences between groups in the Pre-Tilt, Tilt and Post-Tilt phases. However, iRR (ms) was found different between groups. During the Tilt phase, TTP group has shown lower iRR as compared to TTN. Also, TTP and TTN groups exhibited lower iRR and higher LF/HF ratio during Tilt-test as compared to Pre-Tilt phase. Study 3 Comparing the TTP and TTN groups, no statistical differences were found in the LF power of SAP and BRS in both Pre-Tilt and Tilt phases. Following Tilt-test it was observed an increase in LF power of SAP and a reduction in BRS. TTP group showed higher SAP standard deviation during the Tilt phase. In conclusion, study 1 demonstrated that NCS incidence and the time period taken to experience syncope following postural change were not influenced by age and anthropometric characteristics. Study 2 has shown that patients with a history suspicion of NCS, that experienced or not syncope following Tilt-test do not show abnormalities in the sympatovagal balance, but exhibited changes in the iRR. Study 3 showed that the cardiovascular autonomic control (LF-SAP and BRS) is not different between the TTP and TTN groups, in the Pre-Tilt and Tilt phases. Studies 2 and 3 have shown that the methods employed in the analysis of HRV and SAPV were unable to reveal abnormalities in the cardiovascular autonomic modulation in TTP and TTN groups, and thus, can not predict if a patient with a history suspicion of NCS will experience or not syncope during Tilt-test.
109

Implantation ionique dans le GAN pour la réalisation de zones dopées et localisées, de type P / Ionic implantation in GAN to achieve a doped and localized P-type region

Khalfaoui, Wahid 11 July 2016 (has links)
Les problématiques d’économie d’énergie et de diminution des pertes illustrent les limites du Si dans les composants de puissance actuels. Face à ces besoins, le GaN constitue un bon candidat pour la réalisation de nouveaux composants comme les diodes Schottky de puissance. Ainsi, le GREMAN et STMicroelectronics ont entamé une collaboration visant à réaliser une diode Schottky capable de tenir une tension de – 600 V. Or, de nombreux verrous, tels que la forte sensibilité du GaN à la température et les difficultés d’activation de zones localisées dopé de type p (Mg) subsistent encore. Cependant, nous avons mis en évidence l’efficacité de la cap-layer USG/AlN pour la protection du GaN à haute température. Concernant l’activation des dopants de type p par implantation, nous avons démontré que la réduction du « channeling » du Mg nécessite les conditions d’implantation particulière : un tilt de 10° et une épaisseur d’oxyde (USG) de pré-implantation de 200. Parallèlement, nous avons étudié deux procédés d’activation par recuit RTA, mono- et multicycles, et montré leur utilité pour l’activation du dopant. Néanmoins, ce dernier point reste à approfondir. / Energy saving and reduction of losses issues illustrate the current limits of the Si for power devices. To face these needs, GaN is a good candidate for the realization of new components such as Schottky power diodes. GREMAN and STMicroelectronics have worked together to achieve such diodes with 600 V or more breakdown voltages. However, many mandatory milestones, such as GaN temperature sensitivity and the activation problems of localized p-type doped (Mg) zones, must be faced. In this work, we have demonstrated the efficiency of an USG/AlN cap-layer for the protection of GaN facing high-temperature annealing. Concerning the capability to obtain p-type doping by ion implantation, we demonstrate that the reduction of Mg "channeling" effect is achievable using the following conditions: a tilt of 10° and a screening layer (USG) with a thickness of 200 nm. Meanwhile, we have illustrated two activation processes using RTA: single- and multi-cycles annealing. However, activation, after implantation and annealing, has to be investigated in more details.
110

Estudo das características antropométricas e das respostas de frequência cardíaca e pressão arterial, e suas respectivas variabilidades, à manobra postural passiva em pacientes com suspeita clínica de síncope neurocardiogênica / Study of anthropometric characteristics and responses of heart rate and blood pressure, and their variability, induced by passive postural maneuver in patients with clinically suspected neurocardiogenic syncope.

Mariana Adami Leite 03 October 2013 (has links)
A síncope neurocardiogênica (SNC) é caracterizada por perda transitória da consciência e do controle postural, devido a uma hipoperfusão cerebral global de surgimento abrupto, com recuperação rápida e espontânea do paciente ao retornar à posição horizontal. Entretanto, investigações adicionais são necessárias para melhor avaliação das respostas cardiorrespiratórias e autonômicas de pacientes com SNC submetidos ao Tilt-test. O presente estudo teve como objetivo avaliar, em pacientes com história clínica sugestiva de SNC, os efeitos da mudança postural induzidas pelo Tilt-test na pressão arterial (PA) e frequência cardíaca (FC), na variabilidade cardiocirculatória e na sensibilidade barorreflexa (SBR). Além disso, o estudo também avaliou a relação entre a idade, sexo e características antropométricas dos pacientes com as respostas ao Tilt-test, e a relação entre o tempo do início da mudança postural e o momento da síncope, com um ou mais parâmetros acima mencionados. O estudo foi dividido em 3 partes: 1 Estudo retrospectivo de 180 pacientes, com história clínica sugestiva de SNC, mas que apresentaram Tilt-test positivo (TTP) (128 indivíduos) ou negativo (TTN) (52 indivíduos) para síncope; 2 Estudo da variabilidade da frequência cardíaca (VFC), usando-se métodos lineares (Transformada Rápida de Fourier) em pacientes com história clínica sugestiva de SNC, e com respostas positiva ou negativa ao Tilt-test. Foram incluídos 62 pacientes, 31 com Tilt-test positivo e 31 negativo; 3 Estudo da variabilidade da pressão arterial sistólica (VPAS), usando-se métodos lineares (Transformada Rápida de Fourier), e da SBR (Método da Sequência) em pacientes com história clínica sugestiva de SNC, e com respostas positiva ou negativa ao Tilt-test. Foram estudados 33 indivíduos, 16 com Tilt-test positivo e 17 negativo. Estudo 1 Observou-se que a incidência de SNC foi 1,5 vezes maior em mulheres do que em homens. Além disso, os grupos TTP e TTN apresentaram idade e características antropométricas semelhantes entre si, e não houve significância estatística nas correlações entre o tempo do início da posição vertical até a síncope, a idade e as características antropométricas. Estudo 2 Comparando os 2 grupos nos domínios do tempo (SD-iRR, variância-iRR, RMSSD) e da frequência (LF (un), HF (un) e LF/HF) nas fases Pré-Tilt, Tilt e Pós-Tilt, com exceção do iRR (ms), não observou-se diferença entre os grupos. Houve, na fase Tilt, um menor valor do iRR no grupo TTP. O Pré-Tilt comparado ao Tilt, promoveu em ambos os grupos redução do iRR e aumento na razão LF/HF. Estudo 3 Comparando-se os grupos TTP e TTN no Pré-Tilt e Tilt, não houve diferença no LF da PAS e na SBR. O Tilt promoveu, em ambos os grupos, aumento no LF da PAS, redução na SBR. Somente no grupo TTP foi observado aumento no desvio padrão da PAS durante o Tilt. Em conclusão, o estudo 1 demonstrou que a SNC não foi influenciada pela idade e características antropométricas, no que diz respeito à prevalência, e ao tempo de duração entre o início da mudança postural no Tilt-test e o momento do aparecimento da síncope na posição vertical. O estudo 2 demonstrou que indivíduos com suspeita clínica de SNC, e Tilt-test positivo ou negativo não apresentam anormalidades no balanço simpato-vagal cardíaco, mas, apresentaram diferenças no iRR. O estudo 3 não evidenciou diferenças no controle autonômico cardiovascular (LF-PAS e SBR) entre os grupos TTP e TTN no Pré-Tilt e Tilt. Os estudos 2 e 3 mostraram que com a metodologia utilizada na análise da VFC e VPAS não foi possível detectar anormalidades significativas da modulação autonômica cardiovascular nos grupos TTP e TTN, e desse modo, prever na posição vertical do Tilttest, se um paciente com história clínica sugestiva de SNC apresentará ou não síncope. / Neurocardiogenic syncope (NCS) is characterized by transient loss of consciousness and postural control, due to abrupt global cerebral hypoperfusion, with rapid and spontaneous recovery after changing the patient to horizontal position. However, further investigations are necessary to better understand the cardiorespiratory and autonomic responses to the Tilt-test in NCS patients. The present study aimed to evaluate, in patients with a history suspicion of NCS, the effects of postural change (Tilt-test) on blood pressure (BP) and heart rate (HR), on the cardiovascular variability and baroreflex sensitivity (BRS). Furthermore, the study also assessed the relationship between age, sex and anthropometric characteristics with the Tilt-test responses, and the relationship between the time period taken to experience syncope following postural change and the above cited parameters. The study was divided into three parts: 1 A retrospective study with 180 patients with a history suspicion of NCS, that experienced (TTP; 128 individuals) or not (TTN; 52 individuals) syncope following Tilt-test; 2 A study of the heart rate variability (HRV), assessed by linear methods (Fast Fourier Transform), in patients with a history suspicion of NCS and that experienced, or not, syncope following Tilt-test. The study included 62 patients (31 in TTP group and 31 in TTN group); 3 A study of the systolic blood pressure variability (SAPV), using linear methods (Fast Fourier Transform), and of the BRS (Sequence Method) in patients with a history compatible with NCS and that experienced, or not, syncope following Tilt-test. The study included 33 patients (16 in TTP group and 17 in TTN group). Study 1 it was observed that the incidence of NCS was 1.5 times greater in women than in men. Furthermore, groups TTP and TTN showed age and anthropometric characteristics similar to each other and no statistical significance was observed in the correlations among the time period taken to experience syncope following postural change and age and anthropometric characteristics. Study 2 The analysis of the cardiovascular variability, by means of time (SD-iRR, variance-iRR, RMSSD) and frequency (LF (nu), HF (nu) and LF/HF) domain methods, revealed no differences between groups in the Pre-Tilt, Tilt and Post-Tilt phases. However, iRR (ms) was found different between groups. During the Tilt phase, TTP group has shown lower iRR as compared to TTN. Also, TTP and TTN groups exhibited lower iRR and higher LF/HF ratio during Tilt-test as compared to Pre-Tilt phase. Study 3 Comparing the TTP and TTN groups, no statistical differences were found in the LF power of SAP and BRS in both Pre-Tilt and Tilt phases. Following Tilt-test it was observed an increase in LF power of SAP and a reduction in BRS. TTP group showed higher SAP standard deviation during the Tilt phase. In conclusion, study 1 demonstrated that NCS incidence and the time period taken to experience syncope following postural change were not influenced by age and anthropometric characteristics. Study 2 has shown that patients with a history suspicion of NCS, that experienced or not syncope following Tilt-test do not show abnormalities in the sympatovagal balance, but exhibited changes in the iRR. Study 3 showed that the cardiovascular autonomic control (LF-SAP and BRS) is not different between the TTP and TTN groups, in the Pre-Tilt and Tilt phases. Studies 2 and 3 have shown that the methods employed in the analysis of HRV and SAPV were unable to reveal abnormalities in the cardiovascular autonomic modulation in TTP and TTN groups, and thus, can not predict if a patient with a history suspicion of NCS will experience or not syncope during Tilt-test.

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