Tomosynthesis in pulmonary cystic fibrosis with comparison to radiography and computed tomography: a pictorial review

The purpose of this pictorial review is to illustrate chest imaging findings of cystic fibrosis (CF) using tomosynthesis (digital tomography), in comparison to radiography and computed tomography (CT). CF is a chronic systemic disease where imaging has long been used for monitoring chest status. CT exposes the patient to a substantially higher radiation dose than radiography, rendering it unsuitable for the often needed repeated examinations of these patients. Tomosynthesis has recently appeared as an interesting low dose alternative to CT, with an effective dose of approximately 0.08 mSv for children and 0.12 mSv for adults. Tomosynthesis is performed on the same X-ray system as radiography, adding only about 1 min to the normal examination time. Typical pulmonary changes in CF such as mucus plugging, bronchial wall thickening, and bronchiectases are shown in significantly better detail with tomosynthesis than with traditional radiography. In addition, the cost for a tomosynthesis examination is low compared to CT. To reduce the radiation burden of patients with CF it is important to consider low dose alternatives to CT, especially in the paediatric population. Tomosynthesis has a lower radiation dose than CT and gives a superior visualisation of pulmonary CF changes compared to radiography. It is important to further determine the role of tomosynthesis for monitoring disease progression in CF

Analysis of fracture induced scattering of microseismic shear-waves

Fractures are pervasive features within the Earth’s crust and have a significant influence on the multi-physical response of the subsurface. The presence of coherent fracture sets often leads to observable seismic scattering enabling seismic techniques to remotely locate and characterise fracture systems. In this study, we confirm the general scale-dependence of seismic scattering and provide new results specific to shear-wave propagation. We do this by generating full waveform synthetics using finite-difference wave simulation within an isotropic background model containing explicit fractures. By considering a suite of fracture models having variable fracture density and fracture size, we examine the widening effect of wavelets due to scattering within a fractured medium by using several different approaches, such as root-mean-square envelope analysis, shear-wave polarisation distortion, differential attenuation analysis and peak frequency shifting. The analysis allows us to assess the scattering behavior of parametrised models in which the propagation direction is either normal or parallel to the fracture surfaces. The quantitative measures show strong observable deviations for fractures size on the order of or greater than the dominant seismic wavelength within the Mie and geometric scattering regime for both propagation normal and parallel to fracture strike. The results suggest that strong scattering is symptomatic of fractures having size on the same order of the probing seismic wave

Root pruning reduces root competition and increases crop growth in a living mulch cropping system

Living mulch systems may decrease pest attacks. However, the below-ground competition from the living mulch may decrease the growth of the cash crop. Here growth of white cabbage in living mulch systems and in pure stands was compared. Root pruning of the living mulch increased the above-ground biomass of white cabbage, with two prunings giving higher cabbage yields than one. Below-ground growth and competition were examined by measuring root distribution in minirhizotrons and uptake of 15N placed at different soil depths. These studies showed that the ability of mulch species to compete for resources at depth was restricted by pruning

Root pruning reduces root competition in living mulch cropping systems

In intercropping systems with a cash crop and a living mulch intercrop, competition between the cash crop and the intercrop (the living mulch) often reduces the yield of the cash crop. This project investigated (1) the influence of root pruning of living mulches on aboveground biomass of white cabbage. Below-ground growth and competition were examined by measuring (2) root distribution in minirhizotrons and (3) uptake of 15N placed at different soil depths. Two field experiments were carried out at the Aarslev Research Centre in Denmark. These studies showed that the ability of mulch species to compete for resources at depth was restricted by pruning