FISHERIES AND MARINE PROTECTED AREAS: A SPATIAL BIOECONOMIC ANALYSIS OF DISTRIBUTIONAL IMPACTS

Abstract Marine protected areas (MPAs), used increasingly as a tool for conservation of ocean and coastal environments, typically interact with fisheries. Indeed, implementation of an MPA in a coastal region will likely affect fishing communities along that coast but to differing degrees depending on their location relative to the MPA. The resulting creation of “winners” and “losers” has implications for the acceptance and long‐term viability of the MPA. This paper develops a spatially explicit bioeconomic simulation model to assess the distributional implications resulting from creation of a no‐take MPA. The key assumption is that this results in certain fishers being displaced from the MPA to new fishing locations, leading to decreased fishing time and increased costs. Is it possible for those being displaced to end up as “winners” in the fishery? Analysis of the model indicates that such an outcome can occur in certain circumstances, notably if the biological effects of the MPA produce (i) improved ecosystem health inside the MPA, such that fish stock carrying capacity increases; or (ii) to some extent, high fish stock migration rates between neighboring areas. The results indicate that in creating MPAs, careful attention to their design is needed in order to deal with corresponding distributional impacts on fishing communities.     

ACTIVATION KINETICS OF PHOTOSYNTHETIC OXYGEN EVOLUTION UNDER 20–40 NANOSECOND LASER FLASHES

Abstract— Chlorella samples, incubated for varying periods in darkness, were exposed to a series of 20–40 nsec flashes, spaced 15 sec apart, from a Q-switched ruby laser. A stationary Teflon-covered platinum electrode measured the microjet of oxygen produced by each flash. After a dark preincubation exceeding 3 min, at 23°C, little or no oxygen is evolved until the third flash in a sequence. The yields from subsequent flashes increase monotonically until a constant value is reached. If low levels of background light are supplied, or if the interval between series of flashes is decreased, oxygen is evolved on the second or even the first flash. Very similar results were obtained from analogous experiments with tailless 28 μsec flashes from a xenon flashtube. In particular, very little oxygen was evolved from the second flash following a long dark period whatever the spacing between flashes. This means that there are no systematic differences between the effects of saturating 20 nsec and 28 μsec light flashes on the activation processes during the first few flashes following a long dark period. No oscillations of flash yield with successive flashes were observed because of the long interval between flashes. These results are consistent with the idea that the reaction center of Photosystem II must undergo a dark process lasting considerably longer than 28 μsec before it can absorb a second photon.     

On the Finite Element Approximation of an Elliptic Variational Inequality Arising from an Implicit Time Discretization of the Stefan Problem

A semi-discretization in time of the weak formulation of thetwo phase Stefan moving boundary problem results in an ellipticboundary value problem with a non-linear jump discontinuitywhich can be set as an elliptic variational inequality. Thepurpose of this paper is to consider a finite element approximationto the inequality. Assuming that the solution is in H² and thatthe length of the free boundary is finite an error estimateis proved. The resulting algebraic problem is one of solvinga system of nonlinear equations associated with a diagonal multivaluedmonotone mapping. An S.O.R. method is given and shown to beglobally convergent.     

Numerical Studies of the Cahn-Hilliard Equation for Phase Separation

Phase separation in a binary mixture is described by the nonlinearevolutionary Cahn-Hilliard equation. In this paper, we discussthe physical background of the equation and describe its solutionby the Galerkin finite element method. Some theoretical resultsare presented and computationally verified.     

POLY-L-LYSINE-GRAFT-PEG COMB-TYPE POLYCATION COPOLYMERS FOR GENE DELIVERY

ABSTRACT

Polycations have been used for gene delivery in vitro quite successfully, however, in vivo applications suffered from serum effects that lower the overall gene drug efficiency. PEG polymers have been used extensively to minimize serum effects and create “stealth liposomes”, biocompatible materials, and proteins with extended circulation. Here, we report our efforts towards creating “stealth polyplexes”. A comb-type polycation, poly-L-lysine-graft-PEG copolymers were successfully prepared by ring opening of PEG-epoxide with e-amino lysine groups of linear poly-L-lysine. The ratios of PEG-epoxide to poly-L-lysine, PEG-epoxide size (2K, 3K, and 5K), and poly-L-lysine size (10K, 26K, and 38K) were varied. Copolymers with as little as 2% grafted PEG chains sterically stabilized DNA/copolymer complexes (polyplexes) even at charge neutrality. These polyplexes, formed with copolymers with various size of PEG chains grafted on various lenghths of poly-L-lysine backbone, remained relatively small, approximately 100 nm in saline With higher degree of grafting, the binding was significantly diminished. In addition, the morphology of polyplexes changed from thoroidal to more elongated, worm-like forms. Some globular structures were detected in cases of a lower degree of grafting. Finally, DNA release form polyplexes when exposed to negatively charged macromolecules, poly-L-aspartic acid sodium salt, is very structure dependant. Enhanced levels of luciferase expression observed with PLL-PEG polyplexes versus either free DNA or PLL polyplexes are encouraging and warrant further optimization of the polymeric gene delivery system.     

Chebyshev Approximation by A + B* log (1+ CX)

It is shown that best Chebyshev approximations of this formon [0, ] are characterized by alternation of their error curveand are unique.     

Finite-Element Approximation of Elliptic Equations with a Neumann or Robin Condition on a Curved Boundary

This paper considers a finite-element approximation of a second-orderself adjoint elliptic equation in a region Rⁿ (with n=2 or 3)having a curved boundary on which a Neumann or Robin conditionis prescribed. If the finite-element space defined over , a union of elements, has approximation power h^kin the L² norm, and if the region of integration is approximatedby ^h with dist (, ^h)Ch^k, then it is shown that one retains optimalrates of convergence for the error in the H¹ and L² norms, whetherQ^h is fitted or unfitted , provided that the numerical integration scheme has sufficientaccuracy.