Sökresultat

Filtyp

Din sökning på "*" gav 532057 sökträffar

MR imaging, flow and motion

The present work is intended as a nonmathematical review of the role of flow and motion in nuclear magnetic resonance (MR) imaging. A historical review of MR flow measurement techniques is given, followed by a short overview of flow models in vitro and in vivo. The theory behind the influence of motion on the modulus and phase MR signal information is discussed and effects such as washin/washout,

Simulation of the Effect of Inhomogeneities in TEM Transmission Cells using the FDTD-Method

The finite difference time domain (FDTD)-method is applied to model transverse electromagnetic (TEM) transmission cells in three dimensions. The perturbation of the TEM-mode and the standard field distribution in the TEM-cell, due to inhomogeneous materials placed inside the cell cavity, is evaluated. Particularly, the dependence of the disturbance of the TEM-mode on the dimensions of the material

Quantitative assessment of impedance tomography for temperature measurements in hyperthermia

The objective of this study is a non-invasive assessment of the thermal dose in hyperthermia. Electrical impedance tomography (EIT) has previously been given a first trial as a temperature monitoring method together with microwave-induced hyperthermia treatment, but it has not been thoroughly investigated. In the present work we have examined this method in order to investigate the correlation in

A method for MR quantification of flow velocities in blood and CSF using interleaved gradient-echo pulse sequences

The aim of this study was to establish a rapid method for in vivo quantification of a large range of flow velocities using phase information. A basic gradient-echo sequence was constructed, in which flow was encoded along the slice selection direction by variation of the amplitude of a bipolar gradient without changes in sequence timings. The influence of field inhomogeneities and eddy currents wa

A Light Signalling Approach to Node Grouping for Massive MIMO IoT Networks

Massive MIMO is a promising technology to connect very large numbers of energy constrained nodes, as it offers both extensive spatial multiplexing and large array gain. A challenge resides in partitioning the many nodes in groups that can communicate simultaneously such that the mutual interference is minimized. We here propose node partitioning strategies that do not require full channel state in

A descriptive study of pain treatment and its follow-up in primary care of elderly patients after orthopaedic care

Background: Pain treatment post orthopaedic care in the elderly is complicated and requires careful follow-up. Current guidelines state all patients prescribed opioids should have a plan for gradual reduction, with the treatment progressively reduced and ended if any pain remains after more than three months. How this works in primary care remains to be explored.The aim was to describe pain treatm

The role of the understory in litter DOC and nutrient leaching in boreal forests

Dissolved organic carbon (DOC) derived from plant litter plays an important role in the ecosystem carbon balance and soil biogeochemistry. However, in boreal coniferous forests no integrated understanding exists of how understory vegetation contributes to litter leaching of DOC, nitrogen (N) and phosphorus (P) with different bioavailability at the forest stand level. We characterized water extract

Applicability of ultrasonic tomographic technique for progressive damage evaluation in prismatic rock specimen

Several damage processes are associated with the loading of intact rock specimens including closure of existing microcracks, initiation of cracks, and finally development of cracks. Ultrasonic imaging techniques have proven to be very successful in providing relatively high-resolution images of the damage processes in the rock. Ultrasonic velocity tomography is a full-field measurement technique t