Length and colonization rates of roots associated with arbuscular or ectomycorrhizal fungi decline differentially with depth in two northern hardwood forests.

Ectomycorrhizal (EM) and arbuscular mycorrhizal (AM) fungi are often studied independently, and thus little is known regarding differences in vertical distribution of these two groups in forests where they co-occur. We sampled roots at two soil depths in two northern hardwood stands in Bartlett, New Hampshire, co-dominated by tree species that associate with AM or EM fungi. Root length of both groups declined with depth. More importantly, root length of EM plant species exceeded that of AM plants at 0-10-cm depth, while AM exceeded EM root length at 30-50-cm depth. Colonization rates were similar between mineral and organic portions of the shallow (0-10 cm) samples for EM and AM fungi and declined dramatically with depth (30-50 cm). The ratio of EM to AM fungal colonization declined with depth, but not as much as the decline in root length with depth, resulting in greater dominance by EM fungi near the surface and by AM fungi at depth. The depth distribution of EM and AM roots may have implications for soil carbon accumulation as well as for the success of the associated tree species.

Optimizing single-mode collection from pointlike sources of single photons with adaptive optics.

The collection efficiency of light from a point-like emitter may be extremely poor due to aberrations induced by collection optics and the emission distribution of the source. Analyzing the aberrant wavefront (e.g., with a Shack-Hartmann sensor) and correcting accordingly can be infeasible on the single-photon level. We present a technique that uses a genetic algorithm to control a deformable mirror for correcting wavefront aberrations in single-photon signals from point emitters. We apply our technique to both a simulated point source and a real InAs quantum dot, achieving coupling increases of up to 50% and automatic reduction of system drift.

Obturator Anterior Dislocation After Direct Anterior Total Hip Arthroplasty in a Patient with Ehlers-Danlos Syndrome: A Case Report.

CASE: A 71-year-old woman with Ehlers-Danlos syndrome suffered an atraumatic obturator dislocation status post direct anterior total hip arthroplasty. A closed reduction under conscious sedation was attempted, but was unsuccessful. Repeat closed reduction under full general anesthesia with paralysis and fluoroscopic guidance was successful at reducing the femoral prosthesis out of the pelvis and back into an appropriate position. CONCLUSION: Atraumatic obturator dislocations after total hip arthroplasty are exceedingly rare. General anesthesia with full paralysis is helpful for a successful closed reduction, and open reduction may be necessary to remove the femoral prosthesis from the pelvis.