Internationalization strategy of ABotoa/Skypro shoes to United States of America

A Work Project, presented as part of the requirements for the Award of a Masters Degree in Management from the NOVA – School of Business and Economics

Mechanical characterization of aortas using 2D ultrasound elastography

Rupture of aortic aneurysms (AA) is a major cause of death in the Western world. Currently, clinical decision upon surgical intervention is based on the diameter of the aneurysm. However, this method is not fully adequate. Noninvasive assessment of the elastic properties of the arterial wall can be a better predictor for AA growth and rupture risk. The purpose of this study is to estimate mechanical properties of the aortic wall using in vitro inflation testing and 2D ultrasound (US) elastography, and investigate the performance of the proposed methodology for physiological conditions. Two different inflation experiments were performed on twelve porcine aortas: 1) a static experiment for a large pressure range (0 – 140 mmHg); 2) a dynamic experiment closely mimicking the in vivo hemodynamics at physiological pressures (70 – 130 mmHg). 2D raw radiofrequency (RF) US datasets were acquired for one longitudinal and two cross-sectional imaging planes, for both experiments. The RF-data were manually segmented and a 2D vessel wall displacement tracking algorithm was applied to obtain the aortic diameter–time behavior. The shear modulus G was estimated assuming a Neo-Hookean material model. In addition, an incremental study based on the static data was performed to: 1) investigate the changes in G for increasing mean arterial pressure (MAP), for a certain pressure difference (30, 40, 50 and 60 mmHg); 2) compare the results with those from the dynamic experiment, for the same pressure range. The resulting shear modulus G was 94 ± 16 kPa for the static experiment, which is in agreement with literature. A linear dependency on MAP was found for G, yet the effect of the pressure difference was negligible. The dynamic data revealed a G of 250 ± 20 kPa. For the same pressure range, the incremental shear modulus (Ginc) was 240 ± 39 kPa, which is in agreement with the former. In general, for all experiments, no significant differences in the values of G were found between different image planes. This study shows that 2D US elastography of aortas during inflation testing is feasible under controlled and physiological circumstances. In future studies, the in vivo, dynamic experiment should be repeated for a range of MAPs and pathological vessels should be examined. Furthermore, the use of more complex material models needs to be considered to describe the non-linear behavior of the vascular tissue.

Historic and recent occurrences of pinnipeds in the Archipelago of the Azores

The Archipelago of the Azores (Portugal) is located between 378 and 418N and 258 and 318W and crosses the Mid-Atlantic Ridge. It is the most isolated archipelago in the Atlantic, situated 1600 km west of mainland Portugal and 3500 km from the eastern coast of the United States of America. At present, the only population of seals occurring in the Portuguese territory is found on Desertas Islands, Archipelago of Madeira, where a colony of 24 Mediterranean monk seals, Monachus monachus (Hermann, 1779), still persists (Pires and Neves 2001). Nonetheless, historical accounts reported by Frutuoso (1983) dating from the early to late 1500s mention sightings of ‘‘sea wolves’’ (the old Portuguese folk term for the Mediterranean monk seal) at several sites along the Azorean Island of Santa Maria. Little is known about the occurrence of monk seals in this area over the past five centuries, but the species certainly did not escape deliberate killing by the first settlers. While the early monk seal reports by Frutuoso (1983) are the only reports referring to the presence of colonies of seals in the Azores, more recently several sightings and strandings of vagrant seals of other species have been noted.