Development Of An Age-Frequency Distribution For Ocean Quahogs (Arctica Islandica) On Georges Bank

Ocean quahogs [Arctica islandica (Linnaeus, 1769)] are the longest-lived, noncolonial animal known today, with a maximum life span exceeding 500 y. Ocean quahogs are a commercially important bivalve, inhabiting the continental shelf of the North Atlantic Basin. Although considerable information exists on the growth and physiology of A. islandica, limited information is available regarding recruitment; accordingly, sustainably managing the fishery is a challenge. To investigate long-termrecruitment trends, the age of ocean quahogs fromGeorges Bank which were fully recruited to the commercial fishery (\u3e80 mm shell length) was determined by analysis of annual growth lines in the hinge plate. Ages of animals representing the fully recruited size range were used to develop an age-length key, enabling reconstruction of the population age frequency. The population age frequency showed that the Georges Bank population experienced an increase in recruitment beginning in the late 1890s. Initial settlement, documented by a few ocean quahogs that were much older, occurred much earlier, in the early 1800s. Following the late 1890s increase in recruitment, the population expanded rapidly reaching carrying capacity in 20-30 y. Recruitment was more or less continuous after this expansion, consistent with maintenance of a population at carrying capacity. Unusually large year classes were not observed, nor were significant periods of high recruitment interspersed with periods of low recruitment. The relationship of growth rate with age for the oldest clams was assessed using the time series of yearly growth increments and the resulting relationship fitted to three models (von Bertalanffy, Gompertz, and Tanaka\u27s ALOG curve). The ALOG model was clearly superior because it allows for persistent indeterminate growth at old age, rather than the asymptotic behavior of the other two and because it allows for a rapid change in growth rate at what is presumed to be maturity

Critical analysis of the governance of the Sainte Luce Locally Managed Marine Area (LMMA), southeast Madagascar

The Marine Protected Area Governance (MPAG) framework is applied to critically assess the governance of the Sainte Luce Locally Managed Marine Area (LMMA), southeast Madagascar. Madagascar experiences rapid population growth, widespread poverty, corruption and political instability, which hinders natural resource governance. Community-based natural resource management (CBNRM) has been repeatedly employed to circumvent the lack of state capacity. This includes the LMMA model, which has rapidly proliferated, represented by MIHARI, Madagascar's LMMA network. The lobster fishing is the primary source of income for households in the impoverished community of Sainte Luce, one of the key landing sites in the regional export industry. However, fishers, industry actors and available data suggest a significant decline of local and regional stocks, likely due to over-exploitation driven by poverty and migration. In 2013, SEED Madagascar a UK NGO, worked to establish community-based fishery management in Sainte Luce, setting up a local management committee, which introduced a periodic no take zone (NTZ). Despite the community's efforts and some significant achievements, the efficacy of management is limited. To date, limited state support and the lack of engagement by actors throughout the value chain have hampered effective governance. The study reinforces the finding that resilient governance relies on a diversity of actors and the incentives they collectively employ. Here and elsewhere, there is a limit to what can be achieved by bottom-up approaches in isolation. Resilient management of marine resources in Madagascar relies on improving the capacity of community, state, NGO and industry actors to collectively govern resources

Chondrichthyans evolution, diversity and senses.

This book will take you on a journey to discover the origin and diversification of the head, which evolved from a seemingly headless chordate ancestor

ABORDAGEM ESTÉTICA EM DENTES COM AMELOGENESE IMPERFEITA – RELATO DE CASO

Introdução: Paciente NGA, 18 anos, sexo feminino, compareceu a clinica odontológica da UMESP com a queixa principal de “dentes muito amarelos” (sic). Anamnese: A paciente apresentava boas condições sistêmicas e no exame clinico foi observada a presença de dentes hígidos diagnosticados com amelogênese imperfeita. Procedimentos clínicos

Scaling behaviour in spherical shell rotating convection with fixed-flux thermal boundary conditions

Bottom-heated convection in rotating spherical shells provides a simple analogue for many astrophysical and geophysical fluid systems. We construct a database of 74 three-dimensional numerical convection models to investigate the scaling behaviour of seven diagnostics over a range of Ekman and Rayleigh numbers while using a Prandtl number of unity. Our configuration is chosen to model Earth’s core as defined by the fixed flux thermal boundary conditions, radius ratio of and a gravity profile that varies linearly with radius. The quantities of interest are the viscous and thermal boundary layer thickness, mean temperature gradient, mean interior temperature, Nusselt number, horizontal flow length scale, and Reynolds number. We find four parameter regimes characterised by different scaling behaviour. For and low the weakly nonlinear regime is characterised by a balance between viscous, Archimedean and Coriolis forces and the heat transfer is described by weakly nonlinear theory. At low and moderate , the rapidly rotating regime sees inertia take over from viscosity in the global force balance. In this regime the heat transfer scaling has increasing exponent with decreasing Ekman number and shows no saturation to the diffusion free scaling. At high and all the importance of the Coriolis force gradually decreases and all diagnostics continually change in the transitional regime before approaching the scaling behaviour of non-rotating convection

Thermal boundary layer structure in convection with and without rotation

Convection occurs in many settings from metal production to planetary interiors and atmospheres. To understand the dynamics of these systems it is vital to be able to predict the heat transport which is controlled by the thermal boundary layers (TBL). An important issue in the study of convective fluid dynamics is then to determine the temperature distribution within these thin layers in the vicinity of the bounding walls. Deviations from the classical Rayleigh-Bénard convection paradigm such as the addition of rotation or fixed heat-flux (rather than fixed temperature) boundaries compromise the standard ways of defining the width of the TBL. We propose an alternative method for defining the TBL using the location at which the advective and conductive contributions to the heat transport become equal. We show that this method can be robustly applied to two-dimensional (2D) nonrotating convection between no-slip boundaries with fixed temperature or fixed heat-flux thermal boundary conditions and three-dimensional (3D) rotating convection simulations with free-slip boundaries

Sensory neuronal sensitisation occurs through HMGB-1/RAGE and TRPV1 in high glucose conditions

Many potential causes for painful diabetic neuropathy have been proposed including actions of cytokines and growth factors. High mobility group protein B1 (HMGB1) is a RAGE agonist, increased in diabetes, that contributes to pain by modulating peripheral inflammatory responses. HMGB1 enhances nociceptive behaviour in naïve animals through an unknown mechanism. We tested the hypothesis that HMGB1 causes pain through direct neuronal activation of RAGE and alteration of nociceptive neuronal responsiveness. HMGB1 and RAGE expression were increased in skin and primary sensory (DRG) neurons of diabetic rats at times when pain behaviour was enhanced. Agonist-evoked TRPV1-mediated calcium responses increased in cultured DRG neurons from diabetic rats and in neurons from naïve rats exposed to high glucose concentrations. HMGB1-mediated increases in TRPV1-evoked calcium responses in DRG neurons were RAGE and PKC-dependent, and this was blocked by co-administration of the growth factor splice variant, VEGF-A165b. Pain behaviour and DRG RAGE expression increases were blocked by VEGF-A 165 b treatment of diabetic rats in vivo. HMGB-1-RAGE activation sensitizes DRG neurons in vitro. VEGF-A165b blocks HMGB-1/RAGE DRG activation, which may contribute to its analgesic properties in vivo

Using the theory of planned behaviour as a process evaluation tool in randomised trials of knowledge translation strategies : A case study from UK primary care

Peer reviewedPublisher PD