Myosin-V is a two-headed molecular motor taking multiple ATP-dependent steps toward the plus end (forward) of actin filaments. At high mechanical loads, the motor processively steps toward the minus end (backward) even in the absence of ATP, whereas analogous forward steps cannot be induced. The detailed mechanism underlying this mechanical asymmetry is not known. We investigate the effect of f...

The Brown-headed Cowbird (Molothrus ater) is a widespread brood parasite that has attracted considerable recent attention as a possible threat to forestdwelling songbirds (e.g. Finch 1991, Robinson et al. 1995). Cowbirds are unusual among passerines in that their parasitic nature allows some populations to have spatially and temporally separate breeding and feeding activities (Rothstein et al. ...

this paper wants to investigate why fereydūn’s mace was bull-headed. since such weapon has a prominent role in our epics and it has been used by most of our heroes, it seems important to find its origin out.  to achieve this goal, there is a brief explanation about mace and all kinds of it in the texts of different periods in iranian and some other indo-european cultures. then some mythological...

Most studies on similar coexisting species enumerate ecological differences which presumably reduce the demand for common resources and allow coexistence (MacArthur 1958, Root 1967, Stallcup 1968). As Schoener (1974) pointed out, however, these differences alone do not demonstrate the role of competition in structuring avian communities. Even if niches were arranged randomly with respect to one...

Breeding records of Accipiter striatus (Sharp-shinned Hawks) in the southeastern US are scattered and isolated. We documented a Sharp-shinned Hawk and Accipiter cooperii (Cooper’s Hawk) nest while conducting a telemetry study on Melanerpes erythrocephalus (Red-headed Woodpeckers) in Barnwell County, SC in 2006 and 2007. We report the fi rst known nest of a Sharp-shinned Hawk in Barnwell County,...