Notes: Abstract  Background: While potential benefits of robotic technology include decreased morbidity and improved recovery, some have suggested a prohibitively high cost. This study was undertaken to compare actual hospital costs of robotically assisted cardiac procedures with conventional techniques. Methods: We conducted a retrospective review of clinical and financial data of 20 patients who underwent atrial septal defect (ASD) closure and 20 patients who underwent mitral valve repair (MVr) using either robotic techniques or a conventional approach with a sternotomy. Total hospital cost (actual resource consumption) was subdivided into operative and postoperative costs. Results: Robotic technology did not significantly increase total hospital cost for ASD closure or MVr (p = 0.518 and p = 0.539). However, when including the initial capital investment for the robot through amortization of institutional costs, total hospital cost was increased by $3,773 for robotic ASD closure and $3,444 for robotic MVr (p = 0.021 and p = 0.004). The major driver of cost for robotic cases (operating room time) decreased over time. Conclusions: Robotic technology did not significantly increase hospital cost. While the absolute cost for robotic surgery was higher than conventional techniques after taking into account the institutional cost of the robot, the major driver of cost for robotic procedures will likely continue to decrease, as the surgical team becomes increasingly familiar with robotic technology. Furthermore, other benefits, such as improvement in postoperative quality of life and more expeditious return to work may make a robotic approach cost-effective. Thus, it is possible that the benefits of robotic surgery may justify investment in this technology.

Notes: Abstract Most of our knowledge of biodiversity and its causes in the deep-sea benthos derives from regional-scale sampling studies of the macrofauna. Improved sampling methods and the expansion of investigations into a wide variety of habitats have revolutionized our understanding of the deep sea. Local species diversity shows clear geographic variation on spatial scales of 100-1000 km. Recent sampling programs have revealed unexpected complexity in community structure at the landscape level that is associated with large-scale oceanographic processes and their environmental consequences. We review the relationships between variation in local species diversity and the regional-scale phenomena of boundary constraints, gradients of productivity, sediment heterogeneity, oxygen availability, hydrodynamic regimes, and catastrophic physical disturbance. We present a conceptual model of how these interdependent environmental factors shape regional-scale variation in local diversity. Local communities in the deep sea may be composed of species that exist as metapopulations whose regional distribution depends on a balance among global-scale, landscape-scale, and small-scale dynamics. Environmental gradients may form geographic patterns of diversity by influencing local processes such as predation, resource partitioning, competitive exclusion, and facilitation that determine species coexistence. The measurement of deep-sea species diversity remains a vital issue in comparing geographic patterns and evaluating their potential causes. Recent assessments of diversity using species accumulation curves with randomly pooled samples confirm the often-disputed claim that the deep sea supports higher diversity than the continental shelf. However, more intensive quantitative sampling is required to fully characterize the diversity of deep-sea sediments, the most extensive habitat on Earth. Once considered to be constant, spatially uniform, and isolated, deep-sea sediments are now recognized as a dynamic, richly textured environment that is inextricably linked to the global biosphere. Regional studies of the last two decades provide the empirical background necessary to formulate and test specific hypotheses of causality by controlled sampling designs and experimental approaches.