The purpose of this study was to determine whether task-dependent differences in corticospinal pathway excitability occur in going from isolated contractions of the index finger to its coordinated activity with the thumb. Focal transcranial magnetic stimulation (TMS) was used to measure input-output (I/O) curves--a measure of corticospinal pathway excitability--of the contralateral first dorsal...

The nests of some mound-building ants are thought to serve an important function as passive solar collectors. To test this hypothesis, imported fire ant (Solenopsis invicta Buren, S. richteri Forel, and their hybrid) mound shape characteristics (south facing slope angle and area, mound height, and basal elongation in the plane of the ground) were quantified in 2005 and 2006 at a number of locat...

The preservation of thin (<300 mm thick) tephra falls was investigated at four sites in Papua New Guinea (PNG), Alaska and Washington, USA. Measurements of the variations in the thickness of: (i) Tibito Tephra 150 km downwind from the source, Long Island (PNG) erupted mid-seventeenth century; (ii) St Helens W tephra (erupted 1479–80 A.D.) on the slopes of the adjacent Mt. Rainier in Washington ...

The shape of allele-frequency clines maintained by migration-selection balance depends not only on the properties of migration and selection, but also on the dominance relations among alleles and on linkage to other loci under selection. We investigate a two-locus model in which two diallelic, recombining loci are subject to selection caused by an abrupt environmental change. The habitat is one...

Biological market theory models the action of natural selection as a marketplace in which animals are viewed as traders with commodities to offer and exchange. Studies of female Old World monkeys have suggested that grooming might be employed as a commodity to be reciprocated or traded for alternative services, yet previous tests of this grooming-trade model in wild adult male chimpanzees have ...

Retarded accelerations of the self-organized front that separates two steady states of a continuous bistable system are studied by considering the response of the “bistable” front (BF) to the step-like force of flexible steepness. The driven system is described by a nonlinear differential equation of reaction–diffusion type, with the rate function approximated by the linear pieces. The retarded...

[1] Current models of long-term river incision into bedrock suggest that the local rate of differential rock uplift should exert a primary control on the gradient of channel longitudinal profiles. However, discrimination of this effect from the influence of variations in substrate erodibility, sediment flux, precipitation, and transient changes in profile shape has proved difficult in practice....

Abstract As demand for avocado climbs, production in Michoacán—Mexico’s biggest growing region—expands into new places. We use a spatial probit model to project the geographic distribution of likely future expansion and analyze those results determine (a) threats specific forest types (b) how is shifting spatially under current climate scenarios. Our suggest that Michoacán strongly driven by di...