3,237 research outputs found

    The Role of Mesotocin on Social Bonding in Pinyon Jays

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    The neuropeptide oxytocin influences mammalian social bonding by facilitating the building and maintenance of parental, sexual, and same‐sex social relationships. However, we do not know whether the function of the avian homologue mesotocin is evolutionarily conserved across birds. While it does influence avian prosocial behavior, mesotocin\u27s role in avian social bonding remains unclear. Here, we investigated whether mesotocin regulates the formation and maintenance of same‐sex social bonding in pinyon jays (Gymnorhinus cyanocephalus), a member of the crow family. We formed squads of four individually housed birds. In the first, “pair‐formation” phase of the experiment, we repeatedly placed pairs of birds from within the squad together in a cage for short periods of time. Prior to entering the cage, we intranasally administered one of three hormone solutions to both members of the pair: mesotocin, oxytocin antagonist, or saline. Pairs received repeated sessions with administration of the same hormone. In the second, “pair‐maintenance” phase of the experiment, all four members of the squad were placed together in a large cage, and no hormones were administered. For both phases, we measured the physical proximity between pairs as our proxy for social bonding. We found that, compared with saline, administering mesotocin or oxytocin antagonist did not result in different proximities in either the pair‐formation or pair‐maintenance phase of the experiment. Therefore, at the dosages and time frames used here, exogenously introduced mesotocin did not influence same‐sex social bond formation or maintenance. Like oxytocin in mammals, mesotocin regulates avian prosocial behavior; however, unlike oxytocin, we do not have evidence that mesotocin regulates social bonds in birds

    Long Term Stabilization of Expanding Aortic Aneurysms by a Short Course of Cyclosporine A through Transforming Growth Factor-Beta Induction

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    Abdominal aortic aneurysms (AAAs) expand as a consequence of extracellular matrix destruction, and vascular smooth muscle cell (VSMC) depletion. Transforming growth factor (TGF)-beta 1 overexpression stabilizes expanding AAAs in rat. Cyclosporine A (CsA) promotes tissue accumulation and induces TGF -beta1 and, could thereby exert beneficial effects on AAA remodelling and expansion. In this study, we assessed whether a short administration of CsA could durably stabilize AAAs through TGF-beta induction. We showed that CsA induced TGF-beta1 and decreased MMP-9 expression dose-dependently in fragments of human AAAs in vitro, and in animal models of AAA in vivo. CsA prevented AAA formation at 14 days in the rat elastase (diameter increase: CsA: 131.9±44.2%; vehicle: 225.9±57.0%, P = 0.003) and calcium chloride mouse models (diameters: CsA: 0.72±0.14 mm; vehicle: 1.10±0.11 mm, P = .008), preserved elastic fiber network and VSMC content, and decreased inflammation. A seven day administration of CsA stabilized formed AAAs in rats seven weeks after drug withdrawal (diameter increase: CsA: 14.2±15.1%; vehicle: 45.2±13.7%, P = .017), down-regulated wall inflammation, and increased αSMA-positive cell content. Co-administration of a blocking anti-TGF-beta antibody abrogated CsA impact on inflammation, αSMA-positive cell accumulation and diameter control in expanding AAAs. Our study demonstrates that pharmacological induction of TGF-beta1 by a short course of CsA administration represents a new approach to induce aneurysm stabilization by shifting the degradation/repair balance towards healing

    Some flows in shape optimization

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    Geometric flows related to shape optimization problems of Bernoulli type are investigated. The evolution law is the sum of a curvature term and a nonlocal term of Hele-Shaw type. We introduce generalized set solutions, the definition of which is widely inspired by viscosity solutions. The main result is an inclusion preservation principle for generalized solutions. As a consequence, we obtain existence, uniqueness and stability of solutions. Asymptotic behavior for the flow is discussed: we prove that the solutions converge to a generalized Bernoulli exterior free boundary problem

    Surface Gap Soliton Ground States for the Nonlinear Schr\"{o}dinger Equation

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    We consider the nonlinear Schr\"{o}dinger equation (−Δ+V(x))u=Γ(x)∣u∣p−1u(-\Delta +V(x))u = \Gamma(x) |u|^{p-1}u, x∈Rnx\in \R^n with V(x)=V1(x)χ{x1>0}(x)+V2(x)χ{x1<0}(x)V(x) = V_1(x) \chi_{\{x_1>0\}}(x)+V_2(x) \chi_{\{x_1<0\}}(x) and Γ(x)=Γ1(x)χ{x1>0}(x)+Γ2(x)χ{x1<0}(x)\Gamma(x) = \Gamma_1(x) \chi_{\{x_1>0\}}(x)+\Gamma_2(x) \chi_{\{x_1<0\}}(x) and with V1,V2,Γ1,Γ2V_1, V_2, \Gamma_1, \Gamma_2 periodic in each coordinate direction. This problem describes the interface of two periodic media, e.g. photonic crystals. We study the existence of ground state H1H^1 solutions (surface gap soliton ground states) for 0<minâĄÏƒ(−Δ+V)0<\min \sigma(-\Delta +V). Using a concentration compactness argument, we provide an abstract criterion for the existence based on ground state energies of each periodic problem (with V≡V1,Γ≡Γ1V\equiv V_1, \Gamma\equiv \Gamma_1 and V≡V2,Γ≡Γ2V\equiv V_2, \Gamma\equiv \Gamma_2) as well as a more practical criterion based on ground states themselves. Examples of interfaces satisfying these criteria are provided. In 1D it is shown that, surprisingly, the criteria can be reduced to conditions on the linear Bloch waves of the operators −d2dx2+V1(x)-\tfrac{d^2}{dx^2} +V_1(x) and −d2dx2+V2(x)-\tfrac{d^2}{dx^2} +V_2(x).Comment: definition of ground and bound states added, assumption (H2) weakened (sign changing nonlinearity is now allowed); 33 pages, 4 figure

    Flux norm approach to finite dimensional homogenization approximations with non-separated scales and high contrast

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    We consider divergence-form scalar elliptic equations and vectorial equations for elasticity with rough (L∞(Ω)L^\infty(\Omega), Ω⊂Rd\Omega \subset \R^d) coefficients a(x)a(x) that, in particular, model media with non-separated scales and high contrast in material properties. We define the flux norm as the L2L^2 norm of the potential part of the fluxes of solutions, which is equivalent to the usual H1H^1-norm. We show that in the flux norm, the error associated with approximating, in a properly defined finite-dimensional space, the set of solutions of the aforementioned PDEs with rough coefficients is equal to the error associated with approximating the set of solutions of the same type of PDEs with smooth coefficients in a standard space (e.g., piecewise polynomial). We refer to this property as the {\it transfer property}. A simple application of this property is the construction of finite dimensional approximation spaces with errors independent of the regularity and contrast of the coefficients and with optimal and explicit convergence rates. This transfer property also provides an alternative to the global harmonic change of coordinates for the homogenization of elliptic operators that can be extended to elasticity equations. The proofs of these homogenization results are based on a new class of elliptic inequalities which play the same role in our approach as the div-curl lemma in classical homogenization.Comment: Accepted for publication in Archives for Rational Mechanics and Analysi

    Hitting the target: fragment screening with acoustic in situ co-crystallization of proteins plus fragment libraries on pin-mounted data-collection micromeshes

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    A method is presented for screening fragment libraries using acoustic droplet ejection to co-crystallize proteins and chemicals directly on micromeshes with as little as 2.5 nl of each component. This method was used to identify previously unreported fragments that bind to lysozyme, thermolysin, and trypsin

    The MacGyver effect: alive and well in health services research?

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    <p>Abstract</p> <p>Background</p> <p>In a manner similar to the television action hero MacGyver, health services researchers need to respond to the pressure of unpredictable demands and constrained time frames. The results are often both innovative and functional, with the creation of outputs that could not have been anticipated in the initial planning and design of the research.</p> <p>Discussion</p> <p>In the conduct of health services research many challenges to robust research processes are generated as a result of the interface between academic research, health policy and implementation agendas. Within a complex and rapidly evolving environment the task of the health services researcher is, therefore, to juggle sometimes contradictory pressures to produce valid results.</p> <p>Summary</p> <p>This paper identifies the MacGyver-type dilemmas which arise in health services research, wherein innovation may be called for, to maintain the intended scientific method and rigour. These 'MacGyver drivers' are framed as opposing issues from the perspective of both academic and public policy communities. The ideas expressed in this paper are illustrated by four examples from research projects positioned at the interface between public policy strategy and academia.</p
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