Sökning: "pulsatile"

Visar resultat 11 - 15 av 67 avhandlingar innehållade ordet pulsatile.

  1. 11. Nuclear magnetic resonance and microcirculation: The influence of pulsatile brain-tissue motion on measurements of intravoxel incoherent motion and assessment of haemodynamics using exo- and endogenous tracers

    Författare :Ronnie Wirestam; Lund Medicinsk strålningsfysik; []
    Nyckelord :MEDICIN OCH HÄLSOVETENSKAP; MEDICAL AND HEALTH SCIENCES; diagnostic radiology; cortical activation; diffusion; tumor; tumour; ischemic stroke; ischaemic stroke; tracer kinetics; bolus tracking; phase mapping; brain motion; intracranial dynamics; blood flow; haemodynamics; vascularity; MRS; perfusion; MRI; magnetic resonance; Clinical physics; radiology; tomography; medical instrumentation; Klinisk fysiologi; radiologi; tomografi; medicinsk instrumentering;

    Sammanfattning : In this project, the potential of magnetic resonance (MR) imaging and spectroscopy in studies of microcirculation and haemodynamics was evaluated. The spatial and temporal characteristics of human pulsatile brain-tissue movements in healthy individuals, relevant for the understanding of the cerebrospinal-fluid (CSF) circulation and the pathogenesis of hydrocephalus, were thoroughly investigated. LÄS MER

  3. 12. Cerebral perfusion during cardiopulmonary bypass with special reference to blood flow

    Författare :Thomas Tovedal; Fredrik Lennmyr; Stefan Thelin; Dan Lindblom; Uppsala universitet; []
    Nyckelord :MEDICIN OCH HÄLSOVETENSKAP; MEDICAL AND HEALTH SCIENCES;

    Sammanfattning : Cardiopulmonary bypass (CPB) is an important method that enables open heart surgery. There is a risk of neurological complications, and efforts to minimize those include optimization of the cerebral perfusion during CPB. LÄS MER

  4. 13. Cerebral blood flow and intracranial pulsatility studied with MRI : measurement, physiological and pathophysiological aspects

    Författare :Anders Wåhlin; Anders Eklund; Jan Malm; Richard Birgander; William G Bradley; Umeå universitet; []
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Arterial Pulsatility; cerebrospinal fluid; cerebral blood flow; venous flow; intracranial pressure; pulse pressure; dementia; hippocampus; multiple sclerosis; magnetic resonance imaging; radiofysik; radiation physics;

    Sammanfattning : During each cardiac cycle pulsatile arterial blood inflates the vascular bed of the brain, forcing cerebrospinal fluid (CSF) and venous blood out of the cranium. Excessive arterial pulsatility may be part of a harmful mechanism causing cognitive decline among elderly. LÄS MER

  5. 14. Hybrid observers for systems with intrinsic pulse-modulated feedback

    Författare :Diana Yamalova; Alexander Medvedev; Uppsala universitet; []
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Elektroteknik med inriktning mot reglerteknik; Electrical Engineering with specialization in Automatic Control;

    Sammanfattning : This licentiate thesis deals with a special class of hybrid systems, where the continuous linear part is controlled by an intrinsic impulsive feedback that contributes discrete dynamics. The impacting pulsatile feedback signal is not available for measurement and, therefore, has to be reconstructed. LÄS MER

  7. 15. On Identification of Biological Systems

    Författare :Egi Hidayat; Alexander Medvedev; Peter Stoica; Elling Jacobsen; Uppsala universitet; []
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; system identification; biomedical systems; insect vision; endocrine systems; orthogonal basis functions; time delay; impulse response; Laguerre functions; Laguerre polynomials; excitation design; Elektroteknik med inriktning mot reglerteknik; Electrical Engineering with specialization in Automatic Control;

    Sammanfattning : System identification finds nowadays application in various areas of biological research as a tool of empiric mathematical modeling and model individualization. A fundamental challenge of system identification in biology awaits in the form of response variability. LÄS MER