29,096 research outputs found

    Extending the Bajo de Sico, Puerto Rico, Seasonal Closure: An Examination of Small-scale Fishermen’s Perceptions of Possible Socio-economic Impacts on Fishing Practices, Families, and Community

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    Despite considerable conservation efforts, many reef fish fisheries around the world continue to be in peril. Many are vulnerable to overexploitation because they have predictable and highly aggregated spawning events. In U.S. Caribbean waters, fishery managers are increasingly interested in advancing the use of closed areas as a means for rebuilding reef fisheries, protecting coral reef habitats, and furthering ecosystem-based management while maintaining the sustained participation of local fishing communities. This study details small-scale fishermen’s views on the Caribbean Fishery Management Council’s proposals to lengthen the current Bajo de Sico seasonal closure off the west coast of Puerto Rico to afford additional protection to snapper-grouper spawning populations and associated coral reef habitats. Drawing on snowball sampling techniques, we interviewed 65 small-scale fishermen who regularly operate in the Bajo de Sico area. Snowball sampling is a useful method to sample difficult-to-find populations. Our analysis revealed that the majority of the respondents opposed a longer seasonal closure in the Bajo de Sico area, believing that the existing 3-month closure afforded ample protection to reef fish spawning aggregations and that their gear did not impact deep-water corals in the area. Whilst fishermen’s opposition to additional regulations was anticipated, the magnitude of the socio-economic consequences described was unexpected. Fishermen estimated that a year round closure would cause their gross household income to fall between 10% and 80%, with an average drop of 48%. Our findings suggest that policy analysts and decision-makers should strive to better understand the cumulative impacts of regulations given the magnitude of the reported socio-economic impacts; and, more importantly, they should strive to enhance the existing mechanisms by which fishermen can contribute their knowledge and perspectives into the management process

    The inhomogeneous Suslov problem

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    We consider the Suslov problem of nonholonomic rigid body motion with inhomogeneous constraints. We show that if the direction along which the Suslov constraint is enforced is perpendicular to a principal axis of inertia of the body, then the reduced equations are integrable and, in the generic case, possess a smooth invariant measure. Interestingly, in this generic case, the first integral that permits integration is transcendental and the density of the invariant measure depends on the angular velocities. We also study the Painlev\'e property of the solutions.Comment: 10 pages, 5 figure

    Discrete harmonic analysis associated with ultraspherical expansions

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    We study discrete harmonic analysis associated with ultraspherical orthogonal functions. We establish weighted l^p-boundedness properties of maximal operators and Littlewood-Paley g-functions defined by Poisson and heat semigroups generated by certain difference operator. We also prove weighted l^p-boundedness properties of transplantation operators associated to the system of ultraspherical functions. In order to show our results we previously establish a vector-valued local Calder\'on-Zygmund theorem in our discrete setting

    Conical square functions associated with Bessel, Laguerre and Schr\"odinger operators in UMD Banach spaces

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    In this paper we consider conical square functions in the Bessel, Laguerre and Schr\"odinger settings where the functions take values in UMD Banach spaces. Following a recent paper of Hyt\"onen, van Neerven and Portal, in order to define our conical square functions, we use γ\gamma-radonifying operators. We obtain new equivalent norms in the Lebesgue-Bochner spaces Lp((0,),B)L^p((0,\infty ),\mathbb{B}) and Lp(Rn,B)L^p(\mathbb{R}^n,\mathbb{B}), 1<p<1<p<\infty, in terms of our square functions, provided that B\mathbb{B} is a UMD Banach space. Our results can be seen as Banach valued versions of known scalar results for square functions

    Riesz transforms, Cauchy-Riemann systems and amalgam Hardy spaces

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    In this paper we study Hardy spaces Hp,q(Rd)\mathcal{H}^{p,q}(\mathbb{R}^d), 0<p,q<0<p,q<\infty, modeled over amalgam spaces (Lp,q)(Rd)(L^p,\ell^q)(\mathbb{R}^d). We characterize Hp,q(Rd)\mathcal{H}^{p,q}(\mathbb{R}^d) by using first order classical Riesz transforms and compositions of first order Riesz transforms depending on the values of the exponents pp and qq. Also, we describe the distributions in Hp,q(Rd)\mathcal{H}^{p,q}(\mathbb{R}^d) as the boundary values of solutions of harmonic and caloric Cauchy-Riemann systems. We remark that caloric Cauchy-Riemann systems involve fractional derivative in the time variable. Finally we characterize the functions in L2(Rd)Hp,q(Rd)L^2(\mathbb{R}^d) \cap \mathcal{H}^{p,q}(\mathbb{R}^d) by means of Fourier multipliers mθm_\theta with symbol θ(/)\theta(\cdot/|\cdot|), where θC(Sd1)\theta \in C^\infty(\mathbb{S}^{d-1}) and Sd1\mathbb{S}^{d-1} denotes the unit sphere in Rd\mathbb{R}^d.Comment: 24 page

    Solutions of Weinstein equations representable by Bessel Poisson integrals of BMO functions

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    We consider the Weinstein type equation Lλu=0\mathcal{L}_\lambda u=0 on (0,)×(0,)(0,\infty )\times (0,\infty ), where Lλ=t2+x2λ(λ1)x2\mathcal{L}_\lambda=\partial _t^2+\partial _x^2-\frac{\lambda (\lambda -1)}{x^2}, with λ>1\lambda >1. In this paper we characterize the solutions of Lλu=0\mathcal{L}_\lambda u=0 on (0,)×(0,)(0,\infty )\times(0,\infty ) representable by Bessel-Poisson integrals of BMO-functions as those ones satisfying certain Carleson properties

    Lepton flavor violating decays of vector mesons

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    We estimate the rates of lepton flavor violating decays of the vector mesons ρ,ω,ϕeμ\rho, \omega, \phi \to e \mu. The theoretical tools are based on an effective Lagrangian approach without referring to any specific realization of the physics beyond the standard model responsible for lepton flavor violation (\Lfv). The effective lepton-vector meson couplings are extracted from the existing experimental bounds on the nuclear μe\mu^--e^- conversion. In particular, we derive an upper limit for the \Lfv branching ratio Br(ϕeμ)1.3×1021{\rm Br}(\phi \to e \mu) \leq1.3 \times 10^{-21} which is much more stringent than the recent experimental result Br(ϕeμ)<2×106{\rm Br}(\phi \to e \mu) < 2 \times 10^{-6} presented by the SND Collaboration. Very tiny limits on \Lfv decays of vector mesons derived in this letter make direct experimental observation of these processes unrealistic.Comment: 3 pages, 1 figure, accepted for publication in Phys. Rev.
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