Reconstructing Anthropogenic Disturbance Regimes in Forest Ecosystems: A Case Study from the Swiss Rhone Valley

Anthropogenic disturbances of forest ecosystems are increasingly recognized as fundamental ecological processes with important long-term implications for biogeochemical cycles and vegetation patterns. This article aims at reconstructing the extent and intensity of the two most common types of traditional forest uses—forest litter collecting and wood pasture—in the Swiss Rhone valley (Valais) by (i) identifying the spatiotemporal patterns, and (ii) modeling the biomass removal through these practices. Detailed information on agricultural practices and socio-economic context were essential to develop reliable estimates of anthropogenic disturbance regimes. In the Valais, predominately goats and sheep grazed in the forests. The intensity of grazing was a function of the number of grazing animals and the available grazing area. Forest litter was used as bedding for farm animals during the winter. Key factors determining the intensity of litter collecting were the number of animal units, the amount of available substitute products (straw), and the area where litter raking could be practiced. The results show that wood pasture and forest litter collecting were practiced on a significant proportion of the forested landscape in the Valais up to the second half of the 20th century. Until the implementation of forest management plans in the 1930s, almost half of the forests in the study area were affected by wood pasture and/or forest litter collecting. The regulations in the management plans led to an essential reduction of the area available for these traditional practices but likewise to an increased pressure on the remaining areas. The results suggest that the notion of a slow but steady disappearance of traditional non-timber forest uses and the associated effects on forest ecosystems is oversimplified. Quantitative reconstructions of biomass output resulting from these practices confirm the importance of traditional non-timber forest uses for ecosystem development in this region. Furthermore, it is very likely that similar effects have been widespread throughout regions with similar natural and socio-economic context, for example, throughout a significant proportion of the European Alps. This study underlines the importance of environmental history for ecological sciences as well as for forest management and conservation plannin

Joint reconstruction of misaligned images from incomplete measurements for cardiac MRI

Publication in the conference proceedings of SampTA, Bremen, Germany, 201

Myocardial tagging for the analysis left ventricular function

8. Conclusions: Based on our measurements following observations were made: (1) The left ventricle performs a systolic wringing motion which occurs mainly during isovolumic contraction. (2) Diastolic untwisting is found predominantly during isovolumic relaxation and occurs opposite to systolic rotation. (3) After myocardial infarction regional shortening is reduced in infarcted and remote regions. Predominantly diastolic untwisting is delayed and prolonged. (4) In patients with aortic stenosis apical rotation is enhanced, whereas diastolic untwisting is significantly inhibited, which explains the diastolic dysfunction in these patients. Myocardial tagging makes an accurate regional wall motion analysis and the assessment of cardiac rotation possible and, thus, allow new insight into the mechanical function of the hear

A robust broadband fat suppressing phaser T2 preparation module for cardiac magnetic resonance imaging at 3T

Purpose: Designing a new T2 preparation (T2-Prep) module in order to simultaneously provide robust fat suppression and efficient T2 preparation without requiring an additional fat suppression module for T2-weighted imaging at 3T. Methods: The tip-down RF pulse of an adiabatic T2 preparation (T2-Prep) module was replaced by a custom-designed RF excitation pulse that induces a phase difference between water and fat, resulting in a simultaneous T2 preparation of water signals and the suppression of fat signals at the end of the module (now called a phaser adiabatic T2-Prep). Using numerical simulations, in vitro and in vivo ECG-triggered navigator gated acquisitions of the human heart, the blood, myocardium and fat signal-to-noise ratio and right coronary artery (RCA) vessel sharpness using this approach were compared against previously published conventional adiabatic T2-Prep approaches Results: Numerical simulations predicted an increased fat suppression bandwidth and decreased sensitivity against transmit magnetic field inhomogeneities using the proposed approach, while preserving the water T2 preparation capabilities. This was confirmed by the tissue signals acquired on the phantom and the in vivo MRA, which show similar blood and myocardium SNR and CNR and significantly reduced fat SNR compared to the other methods tested. As a result, the RCA conspicuity was significantly increased and the motion artifacts were visually decreased. Conclusion: A novel fat-suppressing T2-preparation method was developed and implemented that demonstrated robust fat suppression and increased vessel sharpness compared with conventional techniques, while preserving its T2 preparation capabilities.Comment: 23 pages, 5 figures, submitted to Magnetic Resonance in Medicin

Reproducibility of 3D free-breathing magnetic resonance coronary vessel wall imaging

Aims Although the coronary artery vessel wall can be imaged non-invasively using magnetic resonance imaging (MRI), the in vivo reproducibility of wall thickness measures has not been previously investigated. Using a refined magnetization preparation scheme, we sought to assess the reproducibility of three-dimensional (3D) free-breathing black-blood coronary MRI in vivo. Methods and results MRI vessel wall scans parallel to the right coronary artery (RCA) were obtained in 18 healthy individuals (age range 25-43, six women), with no known history of coronary artery disease, using a 3D dual-inversion navigator-gated black-blood spiral imaging sequence. Vessel wall scans were repeated 1 month later in eight subjects. The visible vessel wall segment and the wall thickness were quantitatively assessed using a semi-automatic tool and the intra-observer, inter-observer, and inter-scan reproducibilities were determined. The average imaged length of the RCA vessel wall was 44.5±7 mm. The average wall thickness was 1.6±0.2 mm. There was a highly significant intra-observer (r=0.97), inter-observer (r=0.94), and inter-scan (r=0.90) correlation for wall thickness (all P<0.001). There was also a significant agreement for intra-observer, inter-observer, and inter-scan measurements on Bland-Altman analysis. The intra-class correlation coefficients for intra-observer (r=0.97), inter-observer (r=0.92), and inter-scan (r=0.86) analyses were also excellent. Conclusion The use of black-blood free-breathing 3D MRI in conjunction with semi-automated analysis software allows for reproducible measurements of right coronary arterial vessel-wall thickness. This technique may be well-suited for non-invasive longitudinal studies of coronary atherosclerosi