Search

Electrical resistivity tomography (ERT) is increasingly being used to investigate unstable slopes and monitor the hydrogeological processes within. But movement of electrodes or incorrect placement of electrodes with respect to an assumed model can introduce significant resistivity artefacts into the reconstruction. In this work, we demonstrate a joint resistivity and electrode movement reconstruction algorithm within an iterative Gauss-Newton framework. We apply this to ERT monitoring data from an active slow-moving landslide in the UK. Results show fewer resistivity artefacts and suggest that electrode movement and resistivity can be reconstructed at the same time under certain conditions. A new 2.5-D formulation for the electrode position Jacobian is developed and is shown to give accurate numerical solutions when compared to the adjoint method on 3-D models. On large finite element meshes, the calculation time of the newly developed approach was also proven to be orders of magnitude faster than the 3-D adjoint method and addressed modelling errors in the 2-D perturbation and adjoint electrode position Jacobian.

Bovine tuberculosis is usually diagnosed using tuberculin skin tests or at post-mortem. Recently, we have developed a serological test for bovine tuberculosis in cattle which shows a high degree of accuracy using serum samples. Here, we have assessed the performance of the test using individual bovine milk samples. The diagnostic specificity estimate using the high sensitivity setting of the test was 99.7% (95% CI: 99.2–99.9). This estimate was not altered significantly by tuberculin boosting. The relative sensitivity estimates of the test using the high sensitivity setting in milk samples from comparative skin test positive animals was 90.8% (95% CI: 87.1–93.6) with boosting. In animals with lesions, the relative sensitivity was 96.0% (95% CI: 89.6–98.7). Analysis of paired serum and milk samples from skin test positive animals showed correlation coefficients ranging from 0.756–0.955 for individual antigens used in the test. Kappa analysis indicated almost perfect agreement between serum and milk results, while McNemar marginal homogeneity analysis showed no statistically significant differences between the two media. The positive and negative likelihood ratio were 347.8 (95% CI: 112.3–1077.5) and 0.092 (95% CI: 0.07–0.13) respectively for boosted samples from skin test positive animals. The results show that the test has high sensitivity and specificity in individual milk samples and thus milk samples could be used for the diagnosis of bovine tuberculosis. [ABSTRACT FROM AUTHOR]

This study aimed to develop a three-dimensional (3-D) method for assessing ventilation/perfusion (V/Q˙ratios in a pig model of hemodynamic perturbations using electrical impedance tomography (EIT). To evaluate the physiological coherence of changes in EIT-derived V/Q˙ ratios, global EIT-derived V/Q˙mismatches were compared with global gold standards. The study found regional heterogeneity in the distribution of V/Q˙ratios in both the ventrodorsal and craniocaudal directions. Although global EIT-derived indices of V/Q˙mismatch consistently underestimated both low and high V/Q˙mismatch compared with global gold standards, the direction of the change was similar. We made the software available at no cost for other researchers to use. Future studies should compare regional V/Q˙ratios determined by our method against other regional, high-resolution methods. NEW & NOTEWORTHY: In this study, we introduce a novel 3-D method for assessing ventilation-perfusion (V/Q˙) ratios using electrical impedance tomography (EIT). Heterogeneity in V/Q˙ distribution showcases the significant potential for enhanced understanding of pulmonary conditions. This work signifies a substantial step forward in the application of EIT for monitoring and managing lung diseases. [ABSTRACT FROM AUTHOR]