5,313 research outputs found
Experimental evidence for kin-biased helping in a cooperatively breeding vertebrate
The widespread belief that kin selection is necessary for the evolution of cooperative breeding in vertebrates has recently been questioned. These doubts have primarily arisen because of the paucity of unequivocal evidence for kin preferences in cooperative behaviour. Using the cooperative breeding system of long-tailed tits (Aegithalos caudatus) in which kin and non-kin breed within each social unit and helpers are failed breeders, we investigated whether helpers preferentially direct their care towards kin following breeding failure. First, using observational data, we show that not all failed breeders actually become helpers, but that those that do help usually do so at the nest of a close relative. Second, we confirm the importance of kinship for helping in this species by conducting a choice experiment. We show that potential helpers do not become helpers in the absence of close kin and, when given a choice between helping equidistant broods belonging to kin and non-kin within the same social unit, virtually all helped at the nest of kin. This study provides strong evidence that kinship plays an essential role in the maintenance of cooperative breeding in this species
The American Law Institute\u27s Restatement of the Law of Torts with Annotations to the Kentucky Decisions
The American Law Institute\u27s Restatement of the Law of Torts with Annotations to the Kentucky Decisions
Wachovia Bank, N.A. v. Burke: Preemption of State Law with Respect to National Bank Operations Subsidiaries
Wachovia Bank, N.A. v. Burke: Preemption of State Law with Respect to National Bank Operations Subsidiaries
X-ray observations of the galaxy cluster PKS 0745-191: To the virial radius, and beyond
We measure X-ray emission from the outskirts of the cluster of galaxies PKS
0745-191 with Suzaku, determining radial profiles of density, temperature,
entropy, gas fraction, and mass. These measurements extend beyond the virial
radius for the first time, providing new information about cluster assembly and
the diffuse intracluster medium out to ~1.5 r_200, (r_200 ~ 1.7 Mpc ~ 15'). The
temperature is found to decrease by roughly 70 per cent from 0.3-1 r_200. We
also see a flattening of the entropy profile near the virial radius and
consider the implications this has for the assumption of hydrostatic
equilibrium when deriving mass estimates. We place these observations in the
context of simulations and analytical models to develop a better understanding
of non-gravitational physics in the outskirts of the cluster.Comment: 10 pages, 11 figures, accepted to MNRAS; expanded discussion of
analysis and uncertainties, results qualitatively unchange
Optimal integral force feedback and structured PI tracking control : application for objective lens positioner
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