Memorial University of Newfoundland

About: Memorial University of Newfoundland is a education organization based out in St. John's, Newfoundland and Labrador, Canada. It is known for research contribution in the topics: Population & Gadus. The organization has 13818 authors who have published 27785 publications receiving 743594 citations. The organization is also known as: Memorial University & Memorial University of Newfoundland and Labrador.

Timescales for radiation belt electron acceleration and loss due to resonant wave-particle interactions: 1. Theory

Abstract: [1] Radiation belt electrons can interact with various modes of plasma wave in their drift orbits about the Earth, including whistler-mode chorus outside the plasmasphere, and both whistler-mode hiss and electromagnetic ion cyclotron waves inside the plasmasphere. Electrons undergo gyroresonant diffusion in their interactions with these waves. To determine the timescales for electron momentum diffusion and pitch angle diffusion, we develop bounce-averaged quasi-linear resonant diffusion coefficients for field-aligned electromagnetic waves in a hydrogen or multi-ion (H+, He+, O+) plasma. We assume that the Earth's magnetic field is dipolar and that the wave frequency spectrum is Gaussian. Evaluation of the diffusion coefficients requires the solution of a sixth-order polynomial equation for the resonant wave frequencies in the case of a multi-ion (H+, He+, O+) plasma, compared to the solution of a fourth-order polynomial equation for a hydrogen plasma. In some cases, diffusion coefficients for field-aligned waves can provide a valuable approximation for diffusion rates for oblique waves calculated using higher-order resonances. Bounce-averaged diffusion coefficients for field-aligned waves can be evaluated generally in minimal CPU time and can therefore be profitably incorporated into comprehensive kinetic radiation belt codes.

Little left in the tank: metabolic scaling in marine teleosts and its implications for aerobic scope

Abstract: Fish larvae are the world's smallest vertebrates, and their high rates of mortality may be partially owing to a very limited aerobic scope. Unfortunately, however, no complete empirical dataset exists on the relationship between minimal and maximal metabolism (and thus aerobic scope) for any fish species throughout ontogeny, and thus such an association is hard to delineate. We measured standard and maximal metabolism in three marine fish species over their entire life history, and show that while aerobic scope depends greatly on body size and developmental trajectory, it is extremely small during the early life stages (factorial aerobic scope≤1.5). Our findings strongly suggest that limited scope for aerobic activity early in life is likely to constrain physiological function and ultimately impact behaviour and possibly survival. Furthermore, our results have important implications for ecological models that incorporate metabolic scaling, and provide additional evidence against the existence of ‘universal’ scaling exponents.

The Neuroendocrine Regulation of Food Intake in Fish: A Review of Current Knowledge.

Abstract: Fish are the most diversified group of vertebrates and, although progress has been made in the past years, only relatively few fish species have been examined to date, with regards to the endocrine regulation of feeding in fish. In fish, as in mammals, feeding behavior is ultimately regulated by central effectors within feeding centers of the brain, which receive and process information from endocrine signals from both brain and peripheral tissues. Although basic endocrine mechanisms regulating feeding appear to be conserved among vertebrates, major physiological differences between fish and mammals and the diversity of fish, in particular in regard to feeding habits, digestive tract anatomy and physiology, suggest the existence of fish- and species-specific regulating mechanisms. This review provides an overview of hormones known to regulate food intake in fish, emphasizing on major hormones and the main fish groups studied to date.

Ontology and indigeneity: on the political ontology of heterogeneous assemblages

Abstract: The first challenge faced by a project that seeks to bring concerns with ontology and indigeneity into a conversation is to sort out the various (and possibly divergent) projects that are being mobilized when the former term is used, not the least because what do we mean by ontology impinges upon how we can conceive indigeneity. In this article I play a counterpoint between two ‘ontological’ projects: one in geography, that foregrounds a reality conceived as an always-emergent assemblage of human and non-humans and troubles the politics that such assemblages imply. The other in ethnographic theory, that foregrounds that we are not only dealing with a shifting ontology, a (re)animated world, but also with multiple ontologies, a multiplicity of worlds animated in different ways. Thus, if the heterogeneity of always emerging assemblages troubles the political, the very heterogeneity of these heterogeneous assemblages troubles it even more. What kinds of politics and what kinds of knowledges does this troubli...

Human Papillomavirus Testing for Primary Screening of Cervical Cancer Precursors

Abstract: Our objective was to determine whether the addition of human papillomavirus (HPV) testing to screening cytology improves the detection of cervical cancer precursors. Women of ages 18-69 years underwent conventional Pap cytology and HPV DNA testing in a multicenter study in Newfoundland, Canada. Those with positive cytology and/or HPV and a random sample of those with dual negative results were referred for colposcopy. The study enrolled 2098 women. The relative sensitivity of HPV testing was significantly higher than cytology for all-grade squamous intraepithelial lesions [SILs; 73%; 95% confidence interval (CI), 62-82] and high grade SILs (HSILs; 90%; 95% CI, 74-97) but had lower relative specificity (62% for all-grade SILs and 51% for HSILs) than most cytological cutpoints. The rate of combined correct results for all-grade lesions was higher for HPV testing (68.8%) than for any cytological cutpoint (equivocal, 52.3%; LSILs, 51.6%; HSILs, 44.5%). The combination of HPV and an LSIL cutpoint had a negative predictive value of 68% (95% CI, 52-80) for all SILs and 100% (95% CI, 91-100) for HSILs, while referring for colposcopy only 12% of the women. We concluded that HPV testing in conjunction with cytology improved the screening efficacy of cytology alone and may allow for a more effective and safe primary screening program with increased screening intervals.