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 & Context (language use). 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.

Linking swimming performance, cardiac pumping ability and cardiac anatomy in rainbow trout.

Abstract: We exploited the inherent individual diversity in swimming performance of rainbow trout Oncorhynchus mykiss to investigate the hypothesis that maximum cardiac performance is linked to active metabolic rate (AMR) and critical swimming speed (Ucrit). Six hundred juveniles (body mass ~150·g) were screened using a swimming challenge of 1.2·m·s ‐1 to identify ‘poor swimmers’ and ‘good swimmers’, i.e. the first and last 60 fish to fatigue, respectively. These 120 fish were individually tagged and then reared in common tanks for 9 months, where they grew at similar rates and achieved a similar body mass of approximately 1100·g. Critical swimming speed (Ucrit) was then measured individually in tunnel respirometers, with simultaneous recordings of cardiac output via a ventral aortic flow probe. The group of individuals that were screened as poor swimmers remained so, with a significantly (27%) lower Ucrit than good swimmers [89±10·cm·s ‐1 vs 123±5·cm·s ‐1 (mean ± S.E.M.), respectively, N=6], a 19% lower AMR (147±12·µmol·min ‐1 ·kg ‐1 vs 181±11·µmol·min ‐1 ·kg ‐1 , respectively), and a 30% lower maximum in vivo cardiac output (47.3±4.7·ml·min ‐1 ·kg ‐1 vs 68.0±5.2·ml·min ‐1 ·kg ‐1 , respectively). When cardiac performance was compared with an in situ heart preparation, hearts from poor swimmers had a significantly (26%) lower maximum cardiac output (45.9±1.9·ml·min ‐1 ·kg ‐1 vs 56.4±2.3·ml·min ‐1 ·kg ‐1 , respectively) and a 32% lower maximum cardiac power output at a high afterload (3.96±0.58·mW·g ‐1 vs 5.79±1.97·mW·g ‐1 , respectively). Cardiac morphology was

Nonequilibrium clumped isotope signals in microbial methane

Abstract: Methane is a key component in the global carbon cycle, with a wide range of anthropogenic and natural sources. Although isotopic compositions of methane have traditionally aided source identification, the abundance of its multiply substituted "clumped" isotopologues (for example, (13)CH3D) has recently emerged as a proxy for determining methane-formation temperatures. However, the effect of biological processes on methane's clumped isotopologue signature is poorly constrained. We show that methanogenesis proceeding at relatively high rates in cattle, surface environments, and laboratory cultures exerts kinetic control on (13)CH3D abundances and results in anomalously elevated formation-temperature estimates. We demonstrate quantitatively that H2 availability accounts for this effect. Clumped methane thermometry can therefore provide constraints on the generation of methane in diverse settings, including continental serpentinization sites and ancient, deep groundwaters.

Experimental testing of the artificial neural network based protection of power transformers

Abstract: This work presents a novel technique to distinguish between magnetizing inrush and internal fault currents of a power transformer. The proposed differential algorithm is based on an artificial neural network (ANN) and unlike the existing relaying techniques, this method is independent of the harmonic contents of the differential current. A novel neural network is designed and trained using the back-propagation algorithm with experimental data. After training the network, simulation and on-line tests are carried out to evaluate the performance of the ANN based algorithm under different fault and energization conditions. Both simulation and experimental results are quite satisfactory.

Effects of differing intensities of static stretching on jump performance.

Abstract: Acute bouts of static stretching have been shown to impair performance. Most published studies have incorporated static stretching that stressed the muscle(s) to the point of discomfort (POD). There are very few studies that have examined the effects of submaximal intensity (less than POD) static stretching on subsequent performance. Ten participants were pre-tested by performing two repetitions of three different stretches to assess range of motion (ROM) and two repetitions each of five different types of jumps. Following pre-testing, participants were stretched four times for 30 s each with 30 s recovery for the quadriceps, hamstrings and plantar flexors at 100% (POD), 75% and 50% of POD or a control condition. Five minutes following the stretch or control conditions, they were tested post-stretch with the same stretches and jumps as the pre-test. All three stretching intensities adversely affected jump heights. With data collapsed over stretching intensities, there were significant decreases in jump height of 4.6% (P=0.01), 5.7% (P<0.0001), 5.4% (P=0.002), 3.8% (P=0.009) and 3.6% (P=0.008) for the drop jump, squat jump, countermovement jump (CMJ) to a knee flexion of 70 degrees , CMJ using a preferred jump strategy and short amplitude CMJ respectively. An acute bout of maximal or submaximal intensity stretching can impair a variety of jumping styles and based on previous research, it is hypothesized that changes in muscle compliance may play a role.

Urgent preservation of boreal carbon stocks and biodiversity

Abstract: Containing approximately one-third of all remaining global forests, the boreal ecosystem is a crucial store of carbon and a haven for diverse biological communities. Historically, fire and insects primarily drove the natural dynamics of this biome. However, human-mediated disturbances have increased in these forests during recent years, resulting in extensive forest loss for some regions, whereas others face heavy forest fragmentation or threat of exploitation. Current management practices are not likely to maintain the attendant boreal forest communities, nor are they adequate to mitigate climate change effects. There is an urgent need to preserve existing boreal forests and restore degraded areas if we are to avoid losing this relatively intact biodiversity haven and major global carbon sink.