Organ and tissue level properties are more sensitive to age than osteocyte lacunar characteristics in rat cortical bone

Modeling and remodeling induce significant changes of bone structure and mechanical properties with age. Therefore, it is important to gain knowledge of the processes taking place in bone over time. The rat is a widely used animal model, where much data has been accumulated on age-related changes of bone on the organ and tissue level, whereas features on the nano- and micrometer scale are much less explored. We investigated the age-related development of organ and tissue level bone properties such as bone volume, bone mineral density, and load to fracture and correlated these with osteocyte lacunar properties in rat cortical bone. Femora of 14 to 42-week-old female Wistar rats were investigated using multiple complementary techniques including X-ray micro-computed tomography and biomechanical testing. The body weight, femoral length, aBMD, load to fracture, tissue volume, bone volume, and tissue density were found to increase rapidly with age at 14-30 weeks. At the age of 30-42 weeks, the growth rate appeared to decrease. However, no accompanying changes were found in osteocyte lacunar properties such as lacunar volume, ellipsoidal radii, lacunar stretch, lacunar oblateness, or lacunar orientation with animal age. Hence, the evolution of organ and tissue level properties with age in rat cortical bone is not accompanied by related changes in osteocyte lacunar properties. This suggests that bone microstructure and bone matrix material properties and not the geometric properties of the osteocyte lacunar network are main determinants of the properties of the bone on larger length scales

Community resilience in a Danish coastal context : a case study of Løgstør and Thyborøn

Climate change in Denmark is estimated to result in increased precipitation, a rise in sea-level as well as more intense storms. As a result of this, small low-lying coastal communities will be particularly exposed to storm surges. This paper examines how well prepared to handle storm surges two Danish local communities, Løgstør and Thyborøn, are and how they can enhance their community resilience toward storm surges. This was done through field observations, interviews and a conceptual model applied to assess strengths and limitations of the two communities. The focus of this study is on four dimensions of resilience, which are social capital, community capacity, information & communication and institutional capacity. Results from the study indicates that Løgstør is better prepared to handle storm surges than Thyborøn because their strengths are better equipped at preparing for and coping with an impact where as Thyborøn have strengths that are more suitable for a recovery phase. Findings further indicate that Thyborøn should focus on the information & communication dimension of resilience to enhance the community resilience and to improve the flow of information regarding storm surges and the planning process in the municipality to the local community should be the main focus. Løgstør can enhance their community resilience significantly by prioritizing the security over the amenity value and therefore raise the height of the seawall that is protecting the city