Biometric Data and Bone Identification of Topmouth Gudgeon Pseudorasbora Parva and Sunbleak Leucaspius Delineatus

Identification and analysis of the size and composition of prey taken by piscivorous predators assists in the further understanding of ecology of piscivorous fauna (Mann & Beaumont 1980, Hansel et al. 1988, Copp & Roche 2003). Comprehensive evaluation of the digested prey is central to the assessment of predation impacts and is equally important for sustainable fisheries management. Two non-native fish species in England that may be potential prey for native species are sunbleak Leucaspius delineatus (Heckel) and topmouth gudgeon Pseudorasbora parva (Temminck et Schlegel). These species were introduced to English waters in the mid 1980’s (Farr - Cox 1996, Gozlan et al. 2002) where they have since developed extensive populations (Gozlan et al. 2003, Hickley & Chare 2004). Recent studies associate sunbleak and topmouth gudgeon with novel non-native parasites (Beyer et al. 2005, Gozlan et al. 2005). Results such as these have emphasized the need to be able to identify these two species as part of the native predators’ diet. The aim of the study was to provide a tool for species identification and to elaborate the biometric relationships between bone dimensions and body size of sunbleak and topmouth gudgeon. Head bones of fish are particularly useful for identifying the size and composition of prey species from the food remains of predators, as they withstand digestion and are taxonomically valuable (Copp & Kováč 2003)

An in Silico Liver: Model of Gluconeogenesis

An in silico liver was developed in attempt to represent the in vivo state of the fasted liver. It featured two conceptual models. The first one represented carbohydrate metabolism of the human liver, which included the heterogeneous nature of the liver by incorporating spatial variation of key enzyme activities. This model was able to predict the overall fluxes in tissue and the effect of high intensity exercise on the various hepatic fluxes. A second model of hepatic metabolism was developed to represent the complex interplay between gluconeogenesis, lipid metabolism, and alcohol metabolism in the fasted rat liver. Biochemical pathways are represented by key kinetic reactions that include allosteric and substrates effectors, and phosphorylation/dephosphorylation enzymes regulation. The model also incorporates the compartmentation and intercompartmental transports between the cytosol and the mitochondria, and transport of metabolites between blood compartment and the tissue. The model is based on the experimental set-up of fasted perfused rat livers. The model was used to simulate the effects of the two main gluconeogenic substrates available during the fasting state-- lactate and pyruvate--along with the addition of fatty acids and/or ethanol. The model predicts successfully the rates of glucose and ketone production, substrate uptake, and citric acid cycle. Parameter estimations were performed in order to obtain a set of physiological parameters capable of representing the liver under various combinations of nutrients. Parameter sensitivity analysis was generated to quantify the contribution of each parameter to the model output. The model was validated with data available in the published literature from ex vivo studies. The in silico liver constitutes a tool that can be used to predict the effect of physiological stimuli on flux and concentration distributions. This will provide an increase in the understanding of such effects and to determine what parameters, enzymes, and fluxes are responsible

Flow-induced Agitations Create a Granular Fluid

We fluidize a granular medium through localized stirring and probe the mechanical response of quiescent regions far away from the main flow. In these regions the material behaves like a liquid: high-density probes sink, low-density probes float at the depth given by Archimedes' law, and drag forces on moving probes scale linearly with the velocity. The fluid-like character of the material is set by agitations generated in the stirred region, suggesting a non-local rheology: the relation between applied stress and observed strain rate in one location depends on the strain rate in another location

Dewetting dynamics of stressed viscoelastic thin polymer films

Ultrathin polymer films that are produced e.g. by spin-coating are believed to be stressed since polymers are 'frozen in' into out-of-equilibrium configurations during this process. In the framework of a viscoelastic thin film model, we study the effects of lateral residual stresses on the dewetting dynamics of the film. The temporal evolution of the height profiles and the velocity profiles inside the film as well as the dissipation mechanisms are investigated in detail. Both the shape of the profiles and the importance of frictional dissipation vs. viscous dissipation inside the film are found to change in the course of dewetting. The interplay of the non-stationary profiles, the relaxing initial stress and changes in the dominance of the two dissipation mechanisms caused by nonlinear friction with the substrate is responsible for the rich behavior of the system. In particular, our analysis sheds new light on the occurrence of the unexpected maximum in the rim width obtained recently in experiments on PS-PDMS systems.Comment: 11 pages, 10 figure

Frequency Modulation

Contains reports on two research projects

From Frictional to Viscous Behavior: Three Dimensional Imaging and Rheology of Gravitational Suspensions

We probe the three dimensional flow structure and rheology of gravitational (non-density matched) suspensions for a range of driving rates in a split-bottom geometry. We establish that for sufficiently slow flows, the suspension flows as if it were a dry granular medium, and confirm recent theoretical modeling on the rheology of split-bottom flows. For faster driving, the flow behavior is shown to be consistent with the rheological behavior predicted by the recently developed "inertial number approaches for suspension flows.Comment: 5 pages, 4 figures, accepted for Phys. Rev. E. (R

Transient Random Walks in Random Environment on a Galton-Watson Tree

We consider a transient random walk $(X_n)$ in random environment on a Galton--Watson tree. Under fairly general assumptions, we give a sharp and explicit criterion for the asymptotic speed to be positive. As a consequence, situations with zero speed are revealed to occur. In such cases, we prove that $X_n$ is of order of magnitude $n^{\Lambda}$, with $\Lambda \in (0,1)$. We also show that the linearly edge reinforced random walk on a regular tree always has a positive asymptotic speed, which improves a recent result of Collevecchio \cite{Col06}

NorthStar, a support tool for the design and evaluation of quality improvement interventions in healthcare

Background: The Research-Based Education and Quality Improvement (ReBEQI) European partnership aims to establish a framework and provide practical tools for the selection, implementation, and evaluation of quality improvement (QI) interventions. We describe the development and preliminary evaluation of the software tool NorthStar, a major product of the ReBEQI project. Methods: We focused the content of NorthStar on the design and evaluation of QI interventions. A lead individual from the ReBEQI group drafted each section, and at least two other group members reviewed it. The content is based on published literature, as well as material developed by the ReBEQI group. We developed the software in both a Microsoft Windows HTML help system version and a web-based version. In a preliminary evaluation, we surveyed 33 potential users about the acceptability and perceived utility of NorthStar. Results: NorthStar consists of 18 sections covering the design and evaluation of QI interventions. The major focus of the intervention design sections is on how to identify determinants of practice (factors affecting practice patterns), while the major focus of the intervention evaluation sections is on how to design a cluster randomised trial. The two versions of the software can be transferred by email or CD, and are available for download from the internet. The software offers easy navigation and various functions to access the content. Potential users (55% response rate) reported above-moderate levels of confidence in carrying out QI research related tasks if using NorthStar, particularly when developing a protocol for a cluster randomised trial Conclusion: NorthStar is an integrated, accessible, practical, and acceptable tool to assist developers and evaluators of QI interventions