1,815 research outputs found

    A Review and Interspecific Comparison of Nocturnal and Cathemeral Strepsirhine Primate Olfactory Behavioural Ecology

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    This paper provides a comparative review of the known patterns of olfactory behavioural ecology among the nocturnal strepsirhine primates and the cathemeral lemurid genus Eulemur. Endemic to Madagascar, all Eulemur species exhibit both diurnality and nocturnality (i.e., cathemerality), and are gregarious, making them an interesting group of taxa to compare with the nocturnal strepsirhines. This paper represents the first comparative review of patterns of olfactory communication among the nocturnal strepsirhines and the cathemeral Eulemur species. Inductive assessment of these comparative data indicates that olfactory communication serves multiple functions in both groups, including individual recognition, sex recognition, indication of social dominance, and coordination of mating behaviour. However, the urine-washing behaviour characteristic of many nocturnal strepsirhines has no clear homologue among Eulemur species (although the latter may use urine droplets in scent marking). Despite sparse and scattered comparative data, it appears that Eulemur species exhibit different olfactory communication patterns that are associated with differing social organizations in this genus

    Predation and cathemerality. Comparing the impact of predators on the activity patterns of lemurids and ceboids.

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    The removal, or absence, of predatory species could be a contributing proximate factor to the rise of primate cathemerality. But predators themselves can also be cathemeral, so cathemerality could well be an evolutionary stable strategy. From a comparative perspective, it appears that the effect of predatory species cannot provide a unitary explanation for cathemerality. Varying distributions and population densities of predators, especially raptors, may be key factors in owl monkey (Aotus) cathemerality, but temperature and lunar cycle variation have also been implicated. In Madagascar, while raptors are potential predators of lemur species, the cathemerality of Eulemur species coincides with that of the fossa (Cryptoprocta ferox), a major predatory threat to lemurs. Thus, lemurid cathemerality may be more parsimoniously explained as an evolutionary stable strategy

    Υ and Υ′ leptonic widths, abμ, and mb from full lattice QCD

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    We determine the decay rate to leptons of the ground-state ϒ meson and its first radial excitation in lattice QCD for the first time. We use radiatively improved nonrelativistic QCD for the b quarks and include u, d, s and c quarks in the sea with u=d masses down to their physical values. We find Γðϒ → eþe−Þ ¼ 1.19ð11Þ keV and Γðϒ0 → eþe−Þ ¼ 0.69ð9Þ keV, both in good agreement with experimental results. The decay constants we obtain are included in a summary plot of meson decay constants from lattice QCD given in the Conclusions. We also test time moments of the vector current-current correlator against values determined from the b-quark contribution to σðeþe− → hadronsÞ and calculate the b-quark piece of the hadronic vacuum polarization contribution to the anomalous magnetic moment of the muon, ab μ ¼ 0.271ð37Þ × 10−10. Finally we determine the b-quark mass, obtaining in the MS scheme, ¯ m¯ bðm¯ b; nf ¼ 5Þ ¼ 4.196ð23Þ GeV, the most accurate result from lattice QCD to date

    B-meson decay constants: a more complete picture from full lattice QCD

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    We extend the picture of BB-meson decay constants obtained in lattice QCD beyond those of the BB, BsB_s and BcB_c to give the first full lattice QCD results for the BB^*, BsB^*_s and BcB^*_c. We use improved NonRelativistic QCD for the valence bb quark and the Highly Improved Staggered Quark (HISQ) action for the lighter quarks on gluon field configurations that include the effect of u/du/d, ss and cc quarks in the sea with u/du/d quark masses going down to physical values. For the ratio of vector to pseudoscalar decay constants, we find fB/fBf_{B^*}/f_B = 0.941(26), fBs/fBsf_{B^*_s}/f_{B_s} = 0.953(23) (both 2σ2\sigma less than 1.0) and fBc/fBcf_{B^*_c}/f_{B_c} = 0.988(27). Taking correlated uncertainties into account we see clear indications that the ratio increases as the mass of the lighter quark increases. We compare our results to those using the HISQ formalism for all quarks and find good agreement both on decay constant values when the heaviest quark is a bb and on the dependence on the mass of the heaviest quark in the region of the bb. Finally, we give an overview plot of decay constants for gold-plated mesons, the most complete picture of these hadronic parameters to date.Comment: 20 pages, 9 figures. Minor updates to the discussion in several places and some additional reference

    Ion-channel-like behavior in lipid bilayer membranes at the melting transition

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    It is well known that at the gel-liquid phase transition temperature a lipid bilayer membrane exhibits an increased ion permeability. We analyze the quantized currents in which the increased permeability presents itself. The open time histogram shows a "-3/2" power law which implies an open-closed transition rate that decreases like k(t)t1k(t) \propto t^{-1} as time evolves. We propose a "pore freezing" model to explain the observations. We discuss how this model also leads to the 1/fα1/f^{\alpha} noise that is commonly observed in currents across biological and artificial membranes.Comment: 5 pages, 4 figure

    Entropy Production of Brownian Macromolecules with Inertia

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    We investigate the nonequilibrium steady-state thermodynamics of single Brownian macromolecules with inertia under feedback control in isothermal ambient fluid. With the control being represented by a velocity-dependent external force, we find such open systems can have a negative entropy production rate and we develop a mesoscopic theory consistent with the second law. We propose an equilibrium condition and define a class of external forces, which includes a transverse Lorentz force, leading to equilibrium.Comment: 10 pages, 1 figur
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