Global ETD Search
Search theses and dissertations gathered from participating repositories worldwide. Every result links back to the library that holds it. No account is needed.
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Showing 1 to 20 of 31 for “"Pulsatility"”.
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Mathematical modelling of pulsatility in neuroendocrine systems.
The work described in this thesis concerns the mathematical description of the characteristic oscillatory electrical behaviour of certain neurosecretory cells found in the hypothalamus of the mammalian brain. This study concentrates on those cells which secrete the hormone oxytocin. A model first …
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Umbilical arterial flow analysis to determine an index of placental impedance
… literature to characterise the FVW including the Pulsatility Index (PI), the Resistance Index (RI) and more recently, the High Resistance State Index (HRSI). Researchers have shown a dependence of the FVW, and thus the indices which describe it, on factors such as the placental resistance …
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Clinical Applications of Neuromonitoring Following Acute Brain Injury
… microsensor accuracy, compensatory reserve, the pulsatility of brain signals (ICP and TCD), and cerebral arterial blood volume (CaBV) based on TCD. The main results are summarized below: I. Intracranial hypertension has a profound negative influence on cerebrovascular parameters and patient …
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Kisspeptin and neurokinin B in the regulation of the human hypothalamic-pituitary-gonadal axis
… pubertal delay with reduced GnRH/LH pulsatility. Studies in patients with defects in NKB signalling suggest that kisspeptin is functionally downstream of NKB, although there are very limited data on the relevance of the NKB pathway in normal men or women, and no hierarchical data on …
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Effects of Aerobic Exercise on Cognitive and Cerebrovascular Function in Hypertensive Adults
… in arterial stiffness and cerebral hemodynamic pulsatility, and 2) accelerated executive function and memory reaction time post-exercise in adults with and without hypertension. Based on these results, we investigated if adults with hypertension had differential vascular contributions to …
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Transcranial Doppler sonography: a new noninvasive method for measuring toxicant-induced alterations in cerebral blood flow
… systolic-to-diastolic ratio (SDR), Pourcelout pulsatility index (PPI), Gosling pulsatility index (GPI) and systolic upstroke (SU) were calculated using the blood flow velocity waveform. Following the administration of deltamethrin, there was a significant increase in MBFV lasting 10 minutes …
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Clearance systems at brain borders
… glymphatic clearance by regulating arterial pulsatility. Our findings establish novel mechanisms to recruit the glymphatic system to remove brain amyloid.
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A forward model-based analysis of cardiovascular system identification methods
… experimental data in terms of steady-state pulsatility, limiting static behavior, and low frequency hemodynamic variability. We first evaluated the performance of a previously developed cardiovascular system identification method against the forward model.
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Laboratory Development of a Self-Powered Fontan for Treatment of Congenital Heart Disease
… (C). The Fontan MFL is driven with cardiac pulsatility provided by a Harvard Apparatus medical pump. Patient-specific models of the centerpiece of the MFL along with the grafts (IJS) are produced via 3D printing. Baseline values are validated against patient-specific waveforms. Flow and …
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Handedness and the geometry and hemodynamics of the branches of the aortic arch
… and end-diastolic velocity, Resistive index, Pulsatility index, volume flow rate, and vessel diameter. The data was analysed with mixed design ANOVAs, discriminant function analyses, multiple regressions, and paired and independent t-tests, to investigate the asymmetries and predictive …
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High A-scan rate optical coherence tomography angiography for blood flow speed quantification in the retina
… for human retinal imaging. The cardiac pulsatility in α is demonstrated and its synchronization across retinal capillaries is quantified. The repeatability of α measurements is evaluated at multiple spatial levels. This new approach reveals varying α values across different retinal …
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Quantitative Analysis of Retinal Vascular Morphology and Dynamics Using Optical Coherence Tomography
… phenomenon: anisotropic retinal vessel pulsatility, where axial expansion exceeds lateral expansion. Taken together, this work advances OCT-based methods for retinal vascular assessment, contributing new insights for artery-vein classification, vessel morphology quantification, and …
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AVALIAÇÃO ANDROLÓGICA E ULTRASSONOGRAFIA DOPPLER EM GARANHÕES QUARTO DE MILHA
… evaluation Doppler mode, the indexes of pulsatility (PI) and resistivity (RI) were calculated using spectral or pulsed Doppler mode. The blood flow of the pampiniform plexus was evaluated through the Power Doppler mode and the testicular parenchyma through color Doppler mode. The …
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Venous haemodynamic and cerebrospinal fluid anomalies associated with multiple sclerosis
… (iv) MS patients exhibit increased CSF pulsatility in the Aqueduct of Sylvius, which appears to be linked with mild venous hypertension associated with CCSVI; and (v) jugular venous reflux is associated with white matter and parenchymal volumetric changes in Alzheimer’s patients. …
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Effect of head elevation on intracranial blood flow velocity following acute ischemic stroke
… positioning intervention and measurement period. Pulsatility index remained within normal limits in all HOB positions tested indicating that an increase in resistance to blood flow due to increased ICP did not occur with 0 degree positioning. These findings suggest that patients with acute …
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Assessment of Brain Perfusion and Vascular Compliance with Magnetic Resonance Imaging
… with high compliance can better buffer the pulsatility of blood flow, thereby protecting the downstream arterioles and capillaries from damage. Consequently, brain perfusion and vascular compliance are complementary properties of brain's vascular system and may be important indicators of …
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Preeclampsia Link to Gestational Hypoxia
… ultrafiltration, increased uterine artery pulsatility and a reduced ontogenic fall in uterine vascular resistance and in arterial blood pressure with advancing gestation. Downstream adverse consequences on the hypoxic fetus included growth restriction with evidence of brain sparing. …
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Role of von Willebrand factor in shear induced platelet accumulation in a microfluidic device
… of the microfluidic assay, the effect of flow pulsatility on high shear thrombosis was investigated. It was found that steady wall shear rate matched to the mean pulsatile wall shear rate reproduced bulk thrombus formation characteristics of occlusion time, lag time, and thrombus growth rate, …
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Acute Fetal Behavioral Response to Prenatal Yoga: A Single Blinded, Randomized Controlled Trial
… artery systolic-to-diastolic ratio (p=0.34), pulsatility index (p=0.53), or resistance index (p=0.66) between the two groups before and after intervention. Fetal and maternal heart rate, maternal blood pressure and uterine artery Dopplers remained unchanged over time. There was no significant …
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The Effect of Physical Activity on the Insulin Response to Frequent Meals
… subjective appetite ratings; as well as insulin pulsatility were determined. Results: No significant differences in baseline glucose, insulin or c-peptide concentrations across study days were observed (P>0.05). Glucose AUC (12 h and 2 h) were significantly different across study days, with AUC …
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