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
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
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
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
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 -radonifying operators.
We obtain new equivalent norms in the Lebesgue-Bochner spaces and , , in terms of
our square functions, provided that 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
In this paper we study Hardy spaces ,
, modeled over amalgam spaces . We
characterize by using first order classical
Riesz transforms and compositions of first order Riesz transforms depending on
the values of the exponents and . Also, we describe the distributions in
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 by means of Fourier multipliers
with symbol , where and denotes the unit sphere in
.Comment: 24 page
Solutions of Weinstein equations representable by Bessel Poisson integrals of BMO functions
We consider the Weinstein type equation on
, where , with . In
this paper we characterize the solutions of on
representable by Bessel-Poisson integrals of
BMO-functions as those ones satisfying certain Carleson properties
Lepton flavor violating decays of vector mesons
We estimate the rates of lepton flavor violating decays of the vector mesons
. 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 conversion. In
particular, we derive an upper limit for the \Lfv branching ratio which is much more stringent than
the recent experimental result
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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