Kennisvraag H-AKV-139: Fully documented fisheries Initial Advice

This document outlines some initial thoughts on what would be involved in setting up a pilot study for the use of a fully documented fishery (FDF) to allow for a system of catch quota management (CQM) in the North Sea flatfish fishery. Regulatory requirements, practical considerations and some analyses to determine the likely participation within the Dutch beam trawl fleet are also presented

The Effect of Temperature on Drosophila Hybrid Fitness

Mechanisms of reproductive isolation inhibit gene flow between species and can be broadly sorted into two categories: prezygotic and postzygotic. While comparative studies suggest that prezygotic barriers tend to evolve first, postzygotic barriers are crucial for maintaining species boundaries and impeding gene flow that might otherwise cause incipient species to merge. Most, but not all, postzygotic barriers result from genetic incompatibilities between two or more loci from different species, and occur due to divergent evolution in allopatry. Hybrid defects result from improper allelic interactions between these loci. While some postzygotic barriers are environmentally-independent, the magnitude of others has been shown to vary in penetrance depending on environmental factors. We crossed Drosophila melanogaster mutants to two other species, D. simulans and D. santomea, and collected fitness data of the hybrids at two different temperatures. Our goal was to examine the effect of temperature on recessive incompatibility alleles in their genomes. We found that temperature has a stronger effect on the penetrance of recessive incompatibility alleles in the D. simulans genome than on those in the D. santomea genome. These results suggest that the penetrance of hybrid incompatibilities can be strongly affected by environmental context, and that the magnitude of such gene-by-environment interactions can be contingent on the genotype of the hybrid

Enigma of ultraluminous X-ray sources may be resolved by 3D-spectroscopy (MPFS data)

The ultraluminous X-ray sources (ULXs) were isolated in external galaxies for the last 5 years. Their X-ray luminosities exceed 100-10000 times those of brightest Milky Way black hole binaries and they are extremely variable. There are two models for the ULXs, the best black hole candidates. 1. They are supercritical accretion disks around a stellar mass black hole like that in SS433, observed close to the disk axes. 2. They are Intermediate Mass Black Holes (of 100-10000 solar masses). Critical observations which may throw light upon the ULXs nature come from observations of nebulae around the ULXs. We present results of 3D-spectroscopy of nebulae around several ULXs located in galaxies at 3-6 Mpc distances. We found that the nebulae to be powered by their central black holes. The nebulae are shocked and dynamically perturbed probably by jets. The nebulae are compared with SS433 nebula (W50).Comment: Proceedings of the ESO and Euro3D Workshop "Science Perspectives for 3D Spectroscopy", Garching (Germany), October 10-14, 2005. M. Kissler-Patig, M.M. Roth and J.R. Walsh (eds.

Very large dielectric response of thin ferroelectric films with the dead layers

We study the dielectric response of ferroelectric (FE) thin films with "dead" dielectric layer at the interface with electrodes. The domain structure inevitably forms in the FE film in presence of the dead layer. As a result, the effective dielectric constant of the capacitor $\epsilon_{eff}$ increases abruptly when the dead layer is thin and, consequently, the pattern of 180-degree domains becomes "soft". We compare the exact results for this problem with the description in terms of a popular "capacitor" model, which is shown to give qualitatively incorrect results. We relate the present results to fatigue observed in thin ferroelectric films.Comment: 5 pages, REVTeX 3.1 with one eps-figure. A note added that the linear response is not changed by electromechanical effect. To appear in Phys. Rev.

Evaluation of Proposed Amendments to the North Sea Flatfish Multiannual Plan

The evaluation of the multiannual plan is carried out using a numerical simulation model to study the interplay between the biological dynamics of the stocks and the dynamics of the fleet. The biological operating model consists of age structured population models of the ‘true’ plaice and sole stocks in the North Sea, following current stock delineation

Effects of Administering Progesterone and GnRH Before Puberty on Age at Puberty and Reproductive Response in Crossbred Beef Heifers

One hundred six crossbred heifers were utilized to determine prepubertal treatment of progesterone or progesterone plus Gonadotropin Releasing Hormone (GnRH) on age at puberty, conception to a synchronized estrus and conception during the breeding season. Days to puberty were 369.5 ± 6.2, 363.1 ± 9.9 and 360.4 ± 7.8 or control, progesterone primed and progesterone plus Gonadotropin Releasing Hormone (GnRH), respectively. There was no difference (P\u3e.05) in age of puberty, number cycling before synchronization or conception rate during a 35-day breeding season. The percentage of heifers conceiving to synchronized estrus was lower (P\u3c.10) for control compared to progesterone or progesterone plus GnRH treated heifers. Injecting GnRH at breeding had little (P\u3e.05) effect on increasing conception rates to the synchronized estrus or during the breeding season

Anatomy of nuclear shape transition in the relativistic mean field theory

A detailed microscopic study of the temperature dependence of the shapes of some rare-earth nuclei is made in the relativistic mean field theory. Analyses of the thermal evolution of the single-particle orbitals and their occupancies leading to the collapse of the deformation are presented. The role of the non-linear $\sigma-$field on the shape transition in different nuclei is also investigated; in its absence the shape transition is found to be sharper.Comment: REVTEX file (13pages), 12 figures, Phys. Rev. C(in press), \documentstyle[aps,preprint]{revtex