Quantifying Landscape Ruggedness for Animal Habitat Analysis: A Case Study Using Bighorn Sheep in the Mojave Desert

Abstract: Terrain ruggedness is often an important variable in wildlife habitat models. Most methods used to quantify ruggedness are indices derived from measures of slope and, as a result, are strongly correlated with slope. Using a Geographic Information System, we developed a vector ruggedness measure (VRM) of terrain based on a geomorphological method for measuring vector dispersion that is less correlated with slope. We examined the relationship of VRM to slope and to 2 commonly used indices of ruggedness in 3 physiographically different mountain ranges within the Mojave Desert of the southwestern United States. We used VRM, slope, distance to water, and springtime bighorn sheep (Ovis canadensis nelsoni) adult female locations to model sheep habitat in the 3 ranges. Using logistic regression, we determined that the importance of ruggedness in habitat selection remained consistent across mountain ranges, whereas the relative importance of slope varied according to the characteristic physiography of each range. Our results indicate that the VRM quantifies local variation in terrain more independently of slope than other methods tested, and that VRM and slope distinguish 2 different components of bighorn sheep habitat.     

The European Federation of Organisations for Medical Physics. Policy Statement No. 7.1: The roles,responsibilities and status of the medical physicist including the criteria for the staffing levels in a Medical Physics Department approved by EFOMP Council on 5th February 2016

This EFOMP Policy Statement is an amalgamation and an update of the EFOMP Policy Statements No. 2, 4 and 7. It presents guidelines for the roles, responsibilities and status of the medical physicist together with recommended minimum staffing levels. These recommendations take into account the ever-increasing demands for competence, patient safety, specialisation and cost effectiveness of modern healthcare services, the requirements of the European Union Council Directive 2013/59/Euratom laying down the basic safety standards for protection against the dangers arising from exposure to ionising radiation, the European Commission’s Radiation Protection Report No. 174: “Guidelines on medical physics expert”, as well as the relevant publications of the International Atomic Energy Agency. The provided recommendations on minimum staffing levels are in very good agreement with those provided by both the European Commission and the International Atomic Energy Agency.