21,297 research outputs found

    The relationship between metabolic rate and sociability is altered by food-deprivation

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    Individuals vary in the extent to which they associate with conspecifics, but little is known about the energetic underpinnings of this variation in sociability. Group-living allows individuals to find food more consistently, but within groups, there can be competition for food items. Individuals with an increased metabolic rate could display decreased sociability to reduce competition. Long-term food deprivation (FD) may alter any links between sociability and metabolic rate by affecting motivation to find food. We examined these issues in juvenile qingbo carp Spinibarbus sinensis, to understand how FD and metabolic rate affect sociability. Like many aquatic ectotherms, this species experiences seasonal bouts of FD. Individuals were either: (i) food-deprived for 21 days; or (ii) fed a maintenance ration (control). Fish from each treatment were measured for standard metabolic rate (SMR) and tested for sociability twice: once in the presence of a control stimulus shoal and once with a food-deprived stimulus shoal. Control individuals ventured further from stimulus shoals over a 30-min trial, while food-deprived fish did not change their distance from stimulus shoals as trials progressed. Control fish with a higher SMR were least sociable. Well-fed controls showed decreased sociability when exposed to food-deprived stimulus shoals, but there was evidence of consistency in relative sociability between exposures to different shoal types. Results contrast with previous findings that several days of fasting causes individuals to decrease associations with conspecifics. Prolonged FD may cause individuals to highly prioritize food acquisition, and the decreased vigilance that would accompany continuous foraging may heighten the need for the antipredator benefits of shoaling. Conversely, decreased sociability in well-fed fish with a high SMR probably minimizes intraspecific competition, allowing them to satisfy an increased energetic demand while foraging. Together, these results suggest that FD – a challenge common for many ectothermic species – can affect individual sociability as well as the attractiveness of groups towards conspecifics. In addition, the lack of a link between SMR and sociability in food-deprived fish suggests that, in situations where group membership is linked to fitness, the extent of correlated selection on metabolic traits may be context-dependent

    The longitudinal leading-twist distribution amplitude of J/ψJ/\psi meson within background field theory

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    We make a detailed study on the J/ψJ/\psi meson longitudinal leading-twist distribution amplitude ϕ2;J/ψ\phi_{2;J/\psi}^\| by using the QCD sum rules within the background field theory. By keeping all the non-perturbative condensates up to dimension-six, we obtain accurate QCD sum rules for the moments ξn;J/ψ\langle\xi_{n;J/\psi}^\|\rangle. The first three ones are ξ2;J/ψ=0.083(12)\langle\xi_{2;J/\psi}^\|\rangle=0.083(12), ξ4;J/ψ=0.015(5)\langle\xi_{4;J/\psi}^\|\rangle=0.015(5) and ξ6;J/ψ=0.003(2)\langle\xi_{6;J/\psi}^\|\rangle=0.003(2), leading to a single peaked behavior for ϕ2;J/ψ\phi_{2;J/\psi}^\| which is sharper than the previous ones around the region of x0.5x\sim0.5. As an application, we adopt the QCD light-cone sum rules to calculate the BcB_c meson semileptonic decay Bc+J/ψ+νB_c^+ \to J/\psi \ell^+ \nu_\ell. We obtain Γ(Bc+J/ψ+ν)=(89.6719.06+24.76)×1015 GeV\Gamma(B_c^+ \to J/\psi \ell^+ \nu_\ell) = (89.67^{+24.76}_{-19.06}) \times 10^{-15}~{\rm GeV} and (J/ψ+ν)=0.2170.057+0.069\Re(J/\psi \ell^+ \nu_\ell) = 0.217^{+0.069}_{-0.057}, which agree with the next-to-leading order pQCD prediction and the new CDF measurement within errors.Comment: 10 pages, 4 figure

    The DρD\to \rho semileptonic and radiative decays within the light-cone sum rules

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    The measured branching ratio of the DD meson semileptonic decay Dρe+νeD \to \rho e^+ \nu_e, which is based on the 0.82 fb10.82~{\rm fb^{-1}} CLEO data taken at the peak of ψ(3770)\psi(3770) resonance, disagrees with the traditional SVZ sum rules analysis by about three times. In the paper, we show that this discrepancy can be eliminated by applying the QCD light-cone sum rules (LCSR) approach to calculate the DρD\to \rho transition form factors A1,2(q2)A_{1,2}(q^2) and V(q2)V(q^2). After extrapolating the LCSR predictions of these TFFs to whole q2q^2-region, we obtain 1/Vcd2×Γ(Dρeνe)=(55.459.41+13.34)×1015 GeV1/|V_{\rm cd}|^2 \times \Gamma(D \to \rho e \nu_e) =(55.45^{+13.34}_{-9.41})\times 10^{-15}~{\rm GeV}. Using the CKM matrix element and the D0(D+)D^0(D^+) lifetime from the Particle Data Group, we obtain B(D0ρe+νe)=(1.7490.297+0.421±0.006)×103{\cal B} (D^0\to \rho^- e^+ \nu_e) = (1.749^{+0.421}_{-0.297}\pm 0.006)\times 10^{-3} and B(D+ρ0e+νe)=(2.2170.376+0.534±0.015)×103{\cal B} (D^+ \to \rho^0 e^+ \nu_e) = (2.217^{+0.534}_{-0.376}\pm 0.015)\times 10^{-3}, which agree with the CLEO measurements within errors. We also calculate the branching ratios of the two DD meson radiative processes and obtain B(D0ρ0γ)=(1.7440.704+0.598)×105{\cal B}(D^0\to \rho^0 \gamma)= (1.744^{+0.598}_{-0.704})\times 10^{-5} and B(D+ρ+γ)=(5.0340.958+0.939)×105{\cal B}(D^+ \to \rho^+ \gamma) = (5.034^{+0.939}_{-0.958})\times 10^{-5}, which also agree with the Belle measurements within errors. Thus we think the LCSR approach is applicable for dealing with the DD meson decays.Comment: 12 pages, 7 figures, version to be published in EPJ

    Investigation of the properties of nanostructured Li-doped NiO films using the modified spray pyrolysis method

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    The lithium-doped nickel oxide (L-NiO) films were synthetized using the modified spray pyrolysis method with a two-step grown process. By observing the spectra of X-ray photoemission spectroscopy of L-NiO films, the intensity of Ni 2p(3/2) peak of Ni(3+) bonding state increases with increasing Li concentration that causes the decrease of transparency and resistivity. The L-NiO films with optimum characteristics were obtained at Li = 8 at%, where a p-type resistivity of 4.1 × 10(−1) Ω cm and optical transparency above 76% in the visible region are achieved

    Definition of Multi-State Weighted k-out-of-n: F System

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    International audienceThe Multi-state Weighted k-out-of-n System model is the generalization of the Multi-state k-out-of-n System model, which finds wide applications in industry. However only Multi-state Weighted k-out-of-n: G System models have been defined and studied in most recent research works. The mirror image of the Multi-state Weighted k-out-of-n: G System - the Multi-state Weighted k-out-of-n: F System has not been clearly defined and discussed. In this short communication, the basic definition of the Multi-state Weighted k-out-of-n: F System model is proposed. The relationship between the Multi-state Weighted k-out-of-n: G System and the Multi-state Weighted k-out-of-n: F System is also analyzed
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