Reconstructing terrestrial nutrient cycling using stable nitrogen isotopes in wood

Although recent anthropogenic effects on the global nitrogen (N) cycle have been significant, the consequences of increased anthropogenic N on terrestrial ecosystems are unclear. Studies of the impact of increased reactive N on forest ecosystems—impacts on hydrologic and gaseous loss pathways, retention capacity, and even net primary productivity— have been particularly limited by a lack of long-term baseline biogeochemical data. Stable nitrogen isotope analysis (ratio of ¹⁵N to ¹⁴N, termed δ¹⁵N) of wood chronologies offers the potential to address changes in ecosystem N cycling on millennial timescales and across broad geographic regions. Currently, nearly 50 studies have been published utilizing wood δ¹⁵N records; however, there are significant differences in study design and data interpretation. Here, we identify four categories of wood δ¹⁵N studies, summarize the common themes and primary findings of each category, identify gaps in the spatial and temporal scope of current wood δ¹⁵N chronologies, and synthesize methodological frameworks for future research by presenting eight suggestions for common methodological approaches and enhanced integration across studies. Wood δ¹⁵N records have the potential to provide valuable information for interpreting modern biogeochemical cycling. This review serves to advance the utility of this technique for long-term biogeochemical reconstructions

NACA Research Memorandums

Memorandum presenting an investigation of the variations with Mach number and angle of attack of the dynamic rolling-moment characteristics of a slender body of revolution in combination with a cruciform tail in the 6- by 6-foot supersonic wind tunnel. Oscillograph records of the instantaneous rolling moment of the model were obtained for Mach numbers of 0.90, 1.20, 1.40, 1.53, 1.60, and 1.70 at a constant free-stream Reynolds number. Results regarding dynamic rolling moments and visual flow studies are provided

NACA Research Memorandums

Memorandum presenting the aerodynamic characteristics of a model of an air-to-air missile employing variable-incidence cruciform wings of rectangular plan form and a fixed cruciform tail of rectangular plan form, an the characteristics of its body-wing and body-tail components, as determined from a wind-tunnel investigation for Mach numbers of 1.4 and 1.9. The results include normal-force, pitching-moment, and axial-force data for the body-wing-tail, body-wing, and body-tail combinations, and normal-force, hinge-moment, and axial-force data for the individual panels

NACA Research Memorandums

Report presenting the effectiveness of a 50-percent-semispan, constant-percent-chord elevon, and of upper-space spoilers as lateral control surfaces for a wing-fuselage combination with a wing swept back 63 degrees over a range of Mach numbers. For the elevon, results indicated that only about half of the predicted rolling-moment effectiveness was realized. The spoilers were found to be inferior to the elevons for lateral control because of a rapid loss of effectivness above an angle of attack of 4 degrees