Comparisons of global topographic/isostatic models to the Earth's observed gravity field

The Earth's gravitational potential, as described by a spherical harmonic expansion to degree 180, was compared to the potential implied by the topography and its isostatic compensation using five different hypothesis. Initially, series expressions for the Airy/Heiskanen topographic isostatic model were developed to the third order in terms of (h/R), where h is equivalent rock topography and R is a mean Earth radius. Using actual topographic developments for the Earth, it was found that the second and third terms of the expansion contributed 30 and 3 percents, of the first of the expansion. With these new equations it is possible to compute depths (D) of compensation, by degree, using 3 different criteria. The results show that the average depth implied by criterion I is 60 km while it is about 33 km for criteria 2 and 3 with smaller compensation depths at the higher degrees. Another model examined was related to the Vening-Meinesz regional hypothesis implemented in the spectral domain. Finally, oceanic and continental response functions were derived for the global data sets and comparisons made to locally determined values

Competing Forces Framework of Technology Assimilation: An Investigation into a Group of Mobile Device Users

Despite evidence that competing forces shape adoption and assimilation of technologies, there is currently no comprehensive model available that explains how such forces impact individually and socially oriented usage of technology. We distinguish between exploration versus exploitation forces and individual versus social forces and posit that these play key roles in shaping assimilation behaviors and usage outcomes. On this basis, we develop the Competing Forces Framework (CFF) of technology assimilation and validate it by analyzing how a group of fifteen iPhone users assimilated mobile services over a period of seven months. In doing so, we draw on data about the antecedent conditions at the time of iPhone adoption, about interactions within the group and its wider social network, and about how individual usage patterns developed over the considered time period. Based on the analysis, we describe and explain how the iPhone was assimilated into the group. As a result, we offer two distinct contributions to the literature. First, we present the CFF to support further investigation of how assimilation behaviors and usage outcomes are shaped as social groups adopt new technologies. Second, we offer new insight into the forces that shape assimilation of mobile devices into a social group of users. At present the analysis is forthcoming