456 research outputs found

    Modelling fine scale route choice of upstream migrating fish as they approach an instream structure

    Get PDF
    This study used pattern-oriented modelling (POM) to investigate the space use and behavioural response of upstream migrating European river lamprey (Lampetra fluviatilis) to the two-dimensional hydrodynamic conditions created by an instream structure (triangular profile gauging weir). Passive Integrated Transponder (PIT) and acoustic telemetry were used to map the spatial-temporal distribution patterns of lamprey as they migrated upstream. Acoustic Doppler velocimetry and computer modelling were used to quantify the hydrodynamic environment. In adherence with the POM methodology, multiple movement models, incorporating increasingly complex environmental feedback mechanisms and behavioural rules were created and systematically assessed to identify which factors might reproduce the observed patterns. The best model was a spatially explicit Eulerian-Lagrangian Individual Based Model (IBM) that included two simple behaviours: 1) tortuous non-directed swimming when in low flow velocity (< 0.1 m s−1) and 2) persistent directed (against the flow) swimming in moderate to high flow velocity (≄ 0.1 m s−1). The POM indicated that flow heterogeneity was an important influence of lamprey space use and that simple behavioural rules (i.e. two separate movement behaviours in response to flow velocity) were sufficient to reproduce the main movement pattern observed: avoidance of flow recirculating regions near the banks. The combination of field telemetry, hydrodynamic modelling and POM provided a useful framework for systematically identifying the key factors (hydrodynamic and behavioural) that governed the space use of the target species and would likely work well for investigating similar relationships in other aquatic species

    Editorial: state-of-the-art fluorescence image-guided surgery: current and future developments

    Get PDF
    Imaging- and therapeutic targets in neoplastic and musculoskeletal inflammatory diseas

    Nutrient deficiencies in apple plants (Pyrus malus L.)

    Get PDF
    O ensaio foi conduzido com macieiras 'Ohio Beauty' com 1 ano, cultivadas em vaso para se verificar sintomas e nĂ­veis de deficiĂȘncias de N, P, K, Ca, Mg, S e B. Conclui - se que: os nĂ­veis de nutrientes em folhas sadias e com sintomas de deficiĂȘncia sĂŁo: N -2,22 e 1,53%, P - 0,17 e 0,05%; K - 1,32 e 0,22%, Ca - 0,9Âč* e 0,52%, Mg - 0,37 60,06%, S - 0,18 e 0,08%, B - 62 e 2k ppm. Os nĂ­veis de deficiĂȘncia em folhas,a fome oculta" sĂŁo: N - 1,74%, P - 0,07%, K - 0,30%, Ca - 0,65%, Mg - 0,09%, S - 0,09%, B-33ppm.A trial was carried out with one year old 'Ohio Beauty apples (grafted on 'Doucin'), grown on sand cu1ture, receining nutrient solutions lacking the following nutrients at the time: N, P, K, Ca, Mg, S, and B. The main conclusions are as follows: as the adequate and inadequate levels from leaf analysis were, respectively: N -2.22 and 1.53%, P - 0,17 and 0.05%, K - 1.32 and 0.33%; Ca -0.9.4 and 0.52%, Mg - 0.37 and 0.06%; S -0.18 and 0.08%; B -62 and 2k ppm

    Proteinopathies as hallmarks of impaired gene expression, proteostasis and mitochondrial function in amyotrophic lateral sclerosis

    Get PDF
    Amyotrophic lateral sclerosis (ALS) is a fatal adult-onset neurodegenerative disease characterized by progressive degeneration of upper and lower motor neurons. As with the majority of neurodegenerative diseases, the pathological hallmarks of ALS involve proteinopathies which lead to the formation of various polyubiquitylated protein aggregates in neurons and glia. ALS is a highly heterogeneous disease, with both familial and sporadic forms arising from the convergence of multiple disease mechanisms, many of which remain elusive. There has been considerable research effort invested into exploring these disease mechanisms and in recent years dysregulation of RNA metabolism and mitochondrial function have emerged as of crucial importance to the onset and development of ALS proteinopathies. Widespread alterations of the RNA metabolism and post-translational processing of proteins lead to the disruption of multiple biological pathways. Abnormal mitochondrial structure, impaired ATP production, dysregulation of energy metabolism and calcium homeostasis as well as apoptosis have been implicated in the neurodegenerative process. Dysfunctional mitochondria further accumulate in ALS motor neurons and reflect a wider failure of cellular quality control systems, including mitophagy and other autophagic processes. Here, we review the evidence for RNA and mitochondrial dysfunction as some of the earliest critical pathophysiological events leading to the development of ALS proteinopathies, explore their relative pathological contributions and their points of convergence with other key disease mechanisms. This review will focus primarily on mutations in genes causing four major types of ALS (C9ORF72, SOD1, TARDBP/TDP-43, and FUS) and in protein homeostasis genes (SQSTM1, OPTN, VCP, and UBQLN2) as well as sporadic forms of the disease. Finally, we will look to the future of ALS research and how an improved understanding of central mechanisms underpinning proteinopathies might inform research directions and have implications for the development of novel therapeutic approaches

    Out-of-equilibrium quantum fields with conserved charge

    Full text link
    We study the out-of-equilibrium evolution of an O(2)-invariant scalar field in which a conserved charge is stored. We apply a loop expansion of the 2-particle irreducible effective action to 3-loop order. Equations of motion are derived which conserve both total charge and total energy yet allow for the effects of scattering whereby charge and energy can transfer between modes. Working in (1+1)-dimensions we solve the equations of motion numerically for a system knocked out of equilibrium by a sudden temperature quench. We examine the initial stages of the charge and energy redistribution. This provides a basis from which we can understand the formation of Bose-Einstein condensates from first principles.Comment: 11 pages, 5 figures, replacement with improved presentatio

    Core Structure of Global Vortices in Brane World Models

    Full text link
    We study analytically and numerically the core structure of global vortices forming on topologically deformed brane-worlds with a single toroidally compact extra dimension. It is shown that for an extra dimension size larger than the scale of symmetry breaking the magnitude of the complex scalar field at the vortex center can dynamically remain non-zero. Singlevaluedness and regularity are not violated. Instead, the winding escapes to the extra dimension at the vortex center. As the extra dimension size decreases the field magnitude at the core dynamically decreases also and in the limit of zero extra dimension size we reobtain the familiar global vortex solution. Extensions to other types of defects and gauged symmetries are also discussed.Comment: 6 two column pages, 3 figure

    Analysis of shock capturing methods for chemical species transport in unsteady compressible flow

    Full text link
    This paper presents a chemical species transport model to account for variable composition and gas properties along the flow path in internal combustion engines. The numerical solution to adapt the gas dynamic model to chemical species transport in boundary conditions by means of the Method of Characteristics and in volumes by means of a filling and emptying model is described. The performance for chemical species transport in 1D elementsof shock-capturing methods, such as the two-step Lax Wendroff method and the Sweby s TVD scheme considering several flux limiter definitions, is carried out by means of shocktube tests. The influence of the fluid modelling as perfect or non-perfect gas on the numerical methods features and the flow characteristics on shock-tube results are analysed.This work has been partially supported by the Spanish Ministerio de Ciencia e Innovacion through grant number DPI2010-20891-C02-02.Serrano Cruz, JR.; Climent, H.; Piqueras, P.; García Afonso, Ó. (2013). Analysis of shock capturing methods for chemical species transport in unsteady compressible flow. Mathematical and Computer Modelling. 57(7-8):1751-1759. https://doi.org/10.1016/j.mcm.2011.11.026S17511759577-
    • 

    corecore