ON AVOIDANCE ACTIVITIES IN FISHERY ENFORCEMENT MODELS

Compliance and enforcement in fisheries are important issues from an economic point of view since management measures are useless without a certain level of enforcement. These conclusions come from the well‐established theoretical literature on compliance and enforcement problems within fisheries and a common result is that, it is efficient to set fines as high as possible and monitoring as low as possible, when fines are costless and offenders are risk neutral. However, this result is sensitive to the assumption that fishermen cannot engage in avoidance activities, e.g., activities to reduce the likelihood of being detected when noncomplying. The paper presents a model of fisheries that allows the fishermen to engage in avoidance activities. The conclusions from the model are that, under certain circumstances, fines are costly transfers to society since they not only have a direct positive effect on the level of deterrence, but also an indirect negative effect in the form of increased avoidance activities to reduce the probability of detection. The paper contributes to the literature on avoidance activities by introducing the externality from the illegal behavior as an endogenous effect on other offenders. For an externality, that has an exogenous effect on other actors, Malik shows that fines are only costly transfers for conditional deterrence (when one actor is deterred while another actor is not). For fisheries, we show that fines are also costly transfers under no deterrence (when no agents are deterred).     

Transversely isotropic viscoplasticity model for a directionally solidified Ni-base superalloy

A transversely isotropic continuum viscoplasticity model has been formulated to capture the fatigue and creep responses of a directionally solidified (DS) polycrystalline Ni-base superalloy used mainly in turbine blades. This model has been implemented as an ABAQUS User MATerial (UMAT) subroutine using a semi-implicit integration scheme. Isothermal uniaxial fatigue data from tests conducted with and without hold times and creep data are used to characterize the stress–strain response at temperatures ranging from 427 °C to 1038 °C. The scheme leads to reduction of the associated computational costs when compared to a crystal viscoplasticity model that explicitly considers 3-D grain structure. The macroscopic elastoviscoplastic model is shown to simulate the homogenized deformation response of the polycrystalline DS alloy for various isothermal histories. The predictive capability of this model is verified using both in-phase and out-of-phase TMF data, and is compared to the results of analysis of a single crystal in terms of stress concentration and stress distribution for a model problem of a plate with a central hole.     

Kinetic Theory of Vehicular Traffic

Journal of the Operational Research Society -     

Separation of homologous n-alkylammonium hexanoates by reverse-phase thin layer chromatography with continuous development

Long-chain n-alkylammonium hexanoates can be separated according to alkyl chain length by reverse-phase thin layer chromatography on commercially available plates with mixtures of acetonitrile, tetrahydrofuran, and formic acid as developing solvents. Differences in alkyl chain length of two carbon units can be resolved for chain lengths up to 22 carbon units. The use of continuous development for improving resolution has been investigated. An application to the characterization of a ¹⁴C-labeled alkyl-ammonium hexanoate is discussed.     

Coriolis constants of spherical-top molecules from low-temperature infrared studies of vapor band contours: Application to the force field of tungsten hexafluoride

The infrared-active stretching fundamental ν₃ of WF₆ vapor has been studied over the temperature range T = 190–310 K. At lower temperatures the hot-band structure is sufficiently suppressed to allow accurate measurements of the P-R branch spacing, which is a linear function of $\text{T}{}^{\mathrm{<mtext>1</mtext><mtext>2</mtext>}}$. From the slope of a least-squares line fitting 36 measured spacings, the Coriolis constant is found to be ζ₃ = 0.123. Enough overtone and combination bands have been observed in the infrared and laser Raman spectra of WF₆ for harmonic fundamental frequencies to be estimated. Harmonic force constants are calculated, using ζ₃ as the necessary additional constraint in the F_1u symmetry block. Possible sources of error are discussed and error limits are estimated for all reported frequencies and force constants. The valence stretching force constant is ${}_{\mathrm{r}}\text{= 5.50 ± 0.07}\text{mdyn/}\text{A}\text{?}$.     

Thiocyanogen (SCN)2− preparation,ultraviolet photoelectron spectrum and structure

The unstable thiocyanogen molecule, (SCN)₂, has been investigated in the gas phase by ultraviolet photoelection spectroscopy. Semi-empincal and ab intio calculations are used to assist with the orbital assignments and to provide an assessment of the structure A disulphide structure, with a dihedral angle of 87.8° is indicated, similar to those of other well known S₂X₂ molecules.     

A characterization of the minimizer of a function

This paper is intended to give a characterization of the minimum point of a function in terms of the gradient of the function at some other point using some concepts from differential geometry. The function is assumed to have continuous partial derivatives up to and including order four. It is also assumed to have a positive-definite Hessian matrix onR ⁿ and a unique minimum point.