Fire, Fungi, and Beetle Influences on a Lodgepole Pine Ecosystem of South-Central Oregon

Interactions between fire, fungi, bark beetles and lodge- pole pines growing on the pumice plateau of central Oregon are described. Mountain pine beetle (Dendroctonusponderosae) out- breaks occur mainly in forests that are 80-150 years old with a mean diameter of about 25 cm and weakened by a fungus, Phaeolus schweinitzii. The outbreak subsides after most of the large diameter trees are killed. The dead trees fuel subsequent fires which return nutrients to the soil, and a new age class begins. The surviving fire scarred trees are prone to infection by the slow fungal disease and about 100 years later these trees are then susceptible to bark beetle attack

Repeatability of sound evoked triceps myogenic potentials

Objective: To investigate the repeatability of sound-evoked vestibular evoked myogenic potentials recorded from the triceps (tVEMPs) with and without visual feedback. Design: tVEMP responses to 95 dB nHL 500-Hz tone bursts were recorded in a longitudinal, repeated measures study where P1 and N1 latencies and amplitudes were measured on three separate occasions from the same individuals. Analysis of variance, intra-class correlations, and limits of repeatability analyses were used to assess tVEMP repeatability and effects of visual feedback. Study sample: Fifteen participants (nine women) aged between 18 and 41 years took part. Results: Response rates of 63% and 68% were obtained for tVEMPs with eyes open and closed, respectively. When present, tVEMP latencies and amplitudes exhibited fair to good repeatability. Repeatability of tVEMP latencies and amplitudes measured using Bland-Altman methods was poorer with eyes closed. Conclusions: Sound-evoked tVEMP response rates are too low to support their clinical utility at the moment. tVEMP response rate may be improved by refining the balance task to include a force related target. Better tVEMP repeatability with eyes open supports the hypothesis that the response is modulated by visual feedback, and is consistent with studies reporting triceps responses to galvanic stimulation