Forehead-taps elicited short-latency motor responses in the lower leg muscle which, together with vestibulocollic reflexes, might contribute to multisensory control of posture. We tested this paradigm in human subjects standing upright in order to determine if the responses differed depending on whether the taps were to the forehead or temporal bone. Forehead-taps elicited short-latency inhibit...

BACKGROUND Artificial gravity using short-radius centrifugation has been proposed as an integrative countermeasure during spaceflight. OBJECTIVE To determine the rotation parameters of a short-radius centrifuge so that subjects rotating in the dark would feel as if they were standing upright. METHODS Twelve subjects were lying supine in a nacelle on a 2.8 m-radius centrifuge with their head...

Soil microbes play an essential role in the forest ecosystem as an active component. This study examined the hypothesis that soil microbial community structure and metabolic activity would vary with the increasing stand ages in long-term pure plantations of Pinus elliottii. The phospholipid fatty acids (PLFA) combined with community level physiological profiles (CLPP) method was used to assess ...

Aims Aboveground biomass production commonly increases with species richness in plant biodiversity experiments. Little is known about the direct mechanisms that cause this result. We tested if by occupying different heights and depths above and below ground, and by optimizing the vertical distribution of leaf nitrogen, species in mixtures can contribute to increased resource uptake and, thus, i...

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Uneven-aged interior Douglas-fir stand structure and dynamics are complexas a result of irregular fire history, insect and disease outbreaks, and variousforms of partial harvesting and range use. Stocking, crown closure, canopylayering, size-age relationships, and spatial distribution are highly variablefrom one stand to another and within any one stand. Many different factors<l...

Stand structure, species richness and population structures of tree species were characterized in 12 stands representing 50 y of succession following slash-and-burn agriculture in a tropical dry forest in lowland Bolivia. Estimates of tree species richness, canopy cover and basal area reached or surpassed 75% of mature forest levels in the 5-, 8-, and 23-y-old stands respectively. Total stem de...

In order to increase hemlock survivability in stands threatened by hemlock woolly adelgid (HWA), a new study is developing silvicultural thinning guidelines to reduce stand densities, reallocate resources, and increase hemlock vigor across a range of stand types and structures before HWA invasion. The 7 study areas are all geographically similar in that they regularly experience winter temperat...