Modelling diet composition dynamics among North Sea predatory fish using a length-structured partial ecosystem model

Multispecies fisheries management approaches must take account of the array of trophic interactions within the ecosystem. Studies of the gut contents of fish stocks in the North Sea show decadal changes in diet composition, as might be expected when the relative abundances of prey species change. In this paper we explore the extent to which a simple model of prey consumption deployed within a dynamic multi-species population model is able to capture those changes. We make use of a length-structured partial-ecosystem model (FishSUMS) in which the relative preferences of predators for prey are set by a combination of species weightings and predator-to-prey length ratios. The model allows for diets to evolve over the lifetime of the predator species as well as in response to changes in the available prey. Eleven commercially important North Sea species were included in the model with full length structure, together with other trophic resources represented in less detail. The model was simultaneously tuned to various sources of data, including time series of stock biomass and landings. We show that, despite the simplicity of the representation of the predation process, it is capable of capturing some of the large observed changes in diet in four predator species that were sampled during the Year of the Stomach projects in 1981 and 1991: cod, haddock, whiting and saithe. We also quantify how much of the biomass is lost to the fishery, to predation by explicitly-modelled species, and to unspecified mortality

Structure and Function Relationships in a Complex Synthesizing Glycogen de Novo from Ascaris Suum

A complex which synthesized glycogen de novo has been purifiedfrom Ascaris suum. This complex (GS-2) consists of a 66 KDa protein, a 140 KDa protein, and a>330 KDa glycoprotein

The 6dF Galaxy Survey: Dependence of halo occupation on stellar mass

In this paper we study the stellar-mass dependence of galaxy clustering in the 6dF Galaxy Survey. The near-infrared selection of 6dFGS allows more reliable stellar mass estimates compared to optical bands used in other galaxy surveys. Using the Halo Occupation Distribution (HOD) model, we investigate the trend of dark matter halo mass and satellite fraction with stellar mass by measuring the projected correlation function, $w_p(r_p)$. We find that the typical halo mass ($M_1$) as well as the satellite power law index ($\alpha$) increase with stellar mass. This indicates, (1) that galaxies with higher stellar mass sit in more massive dark matter halos and (2) that these more massive dark matter halos accumulate satellites faster with growing mass compared to halos occupied by low stellar mass galaxies. Furthermore we find a relation between $M_1$ and the minimum dark matter halo mass ($M_{\rm min}$) of $M_1 \approx 22\,M_{\rm min}$, in agreement with similar findings for SDSS galaxies. The satellite fraction of 6dFGS galaxies declines with increasing stellar mass from 21% at $M_{\rm stellar} = 2.6\times10^{10}h^{-2}\,M_{\odot}$ to 12% at $M_{\rm stellar} = 5.4\times10^{10}h^{-2}\,M_{\odot}$ indicating that high stellar mass galaxies are more likely to be central galaxies. We compare our results to two different semi-analytic models derived from the Millennium Simulation, finding some disagreement. Our results can be used for placing new constraints on semi-analytic models in the future, particularly the behaviour of luminous red satellites. Finally we compare our results to studies of halo occupation using galaxy-galaxy weak lensing. We find good overall agreement, representing a valuable crosscheck for these two different tools of studying the matter distribution in the Universe.Comment: 17 pages, 11 figures. arXiv admin note: text overlap with arXiv:1104.2447 by other author

Algebraic Classical and Quantum Field Theory on Causal Sets

The framework of perturbative algebraic quantum field theory (pAQFT) is used to construct QFT models on causal sets. We discuss various discretised wave operators, including a new proposal based on the idea of a `preferred past', which we also introduce, and show how they may be used to construct classical free and interacting field theory models on a fixed causal set; additionally, we describe how the sensitivity of observables to changes in the background causal set may be encapsulated in a relative Cauchy evolution. These structures are used as the basis of a deformation quantization, using the methods of pAQFT. The SJ state is defined and discussed as a particular quantum state on the free quantum theory. Finally, using the framework of pAQFT, we construct interacting models for arbitrary interactions that are smooth functions of the field configurations. This is the first construction of such a wide class of models achieved in QFT on causal sets.Comment: 42 pages, 3 figure

Introduction to conceptual explorations on person-centered medicine

Contains fulltext : 87938.pdf (publisher's version ) (Open Access

Modelling the sensitivity of suspended sediment profiles to tidal current and wave conditions

Seawater turbidity due to suspended particulate material (SPM) is an important property of a marine ecosystem, determining the underwater light environment and many aspects of biological production and ecology. SPM concentrations are largely determined by patterns of sediment resuspension from the seabed due to shear stress caused by waves and currents. Hence planning for the construction of large scale offshore structures which will alter regional hydrodynamics needs to consider the consequences for SPM concentrations. Here we develop a one-dimensional (vertical) model of SPM dynamics which can be used to scope the effects of changes in wave and tidal current properties at a site. We implement the model for a number of sites off the east coast of Scotland where we have extensive data sets to enable numerical parameter optimisation. The model performs well at simulating fluctuations in turbidity varying from flood-ebb tidal cycles, spring-neap cycles, storm wave events, and an annual cycle of SPM concentration which is attributed to seasonal consolidation of seabed sediments. Sensitivity analysis shows that, for the range of seabed sediment types in the study (water depth 16 – 50 m; mud content 0.006 – 0.380 proportion by weight), relatively large (50%) attenuations of tidal current speed are required to produce changes in water column turbidity which would be detectable by observations given the variability in measurements. The model has potential for application to map the large scale sensitivity of turbidity distributions to the installation of wave and tidal energy extraction arrays

Modelling wave-current interactions off the east coast of Scotland

Densely populated coastal areas of the North Sea are particularly vulnerable to severe wave conditions, which overtop or damage sea-defences leading to dangerous flooding. Around the shallow southern North Sea, where the coastal margin is low-lying and population density is high, oceanographic modelling has helped to develop forecasting systems to predict flood risk. However coastal areas of the deeper northern North Sea are also subject to regular storm damage but there has been little or no effort to develop coastal wave models for these waters. Here we present a high spatial resolution model of northeast Scottish coastal waters, simulating waves and the effect of tidal currents on wave propagation, driven by global ocean tides, far-field wave conditions, and local air pressure and wind stress. We show that the wave- current interactions and wave-wave interactions are particularly important for simulating the wave conditions close to the coast at various locations. The model can simulate the extreme conditions experienced when high (spring) tides are combined with sea-level surges and large Atlantic swell. Such a combination of extremes represents a high risk for damaging conditions along the Scottish coast

Communication of multi-modal imaging: MRI, MSI, and histology

In an environment where patients are expecting increasingly more information about their condition and care pathway, this tool offers the potential for visual multi-model confirmation of findings. Both normal and abnormal tissue are clearly identified, confirmed by multiple tests, enabling the healthcare professional to easily demonstrate to the patient the effects of treatment