This report presents Aspen. Sandia National Laboratories is developing this new agentbased macroeconomic simulation model of the U.S. economy. The model is notable because it allows a large number of individual economic agents to be modeled at a high level of detail and with a great degree of freedom. Some features of Aspen are (a) a sophisticated message-passing system that allows individual p...

Stanford University, Freeman Spogli Institute for International Studies and Center for Innovation in Global Health, Stanford, CA, USA (RG); Global Health Corps, New York, NY, USA (BPB, EM); The Aspen Institute, Impact Careers Initiative, Aspen, CO, USA (JD); Partners In Health, Cambridge, MA, USA (CvdhH, PEF); Harvard Medical School, Global Health Delivery Partnership, Boston, MA, USA (CvdhH); ...

Quaking aspens (Populus tremuloides Michx.) are found in diverse habitats throughout North America. While the biogeography of aspens' distribution has been documented, the drivers of the phenotypic diversity of aspen are still being explored. In our study, we examined differences in climate between northern and southwestern populations of aspen, finding large-scale differences between the popul...

Studies of the Populus tremuloides root system by Day (1944), Sandberg (1951) and Barnes (1959) have all shown lateral roots extending as much as 30 feet from tree base. These roots may branch extensively and sometimes exhibit an "undulating" growth habit. According to the above authors, suckers occur on the segments of these lateral roots which are closest to the soil surface. The objective of...

ACKNOWLEDGEMENTS AGCI gratefully acknowledges the assistance of Sue Bookhout and Michelle Masone in preparing the report, and the workshop participants for their contributions and edits. More information about the workshop, including individual presentations, and background papers, and DVDs of talks are available at The views expressed in this report are based on summaries of workshop participa...