University of Exeter

About: University of Exeter is a education organization based out in Exeter, United Kingdom. It is known for research contribution in the topics: Population & Climate change. The organization has 15820 authors who have published 50650 publications receiving 1793046 citations. The organization is also known as: Exeter University & University of the South West of England.

Recent variability of the global ocean carbon sink

Abstract: We present a new observation-based estimate of the global oceanic carbon dioxide (CO2) sink and its temporal variation on a monthly basis from 1998 through 2011 and at a spatial resolution of 1×1. This sink estimate rests upon a neural network-based mapping of global surface ocean observations of the partial pressure of CO2 (pCO2) from the Surface Ocean CO2 Atlas database. The resulting pCO2 has small biases when evaluated against independent observations in the different ocean basins, but larger randomly distributed differences exist particularly in high latitudes. The seasonal climatology of our neural network-based product agrees overall well with the Takahashi et al. (2009) climatology, although our product produces a stronger seasonal cycle at high latitudes. From our global pCO2 product, we compute a mean net global ocean (excluding the Arctic Ocean and coastal regions) CO2 uptake flux of −1.42 ± 0.53 Pg C yr−1, which is in good agreement with ocean inversion-based estimates. Our data indicate a moderate level of interannual variability in the ocean carbon sink (±0.12 Pg C yr−1, 1𝜎) from 1998 through 2011, mostly originating from the equatorial Pacific Ocean, and associated with the El Nino–Southern Oscillation. Accounting for steady state riverine and Arctic Ocean carbon fluxes our estimate further implies a mean anthropogenic CO2 uptake of −1.99 ± 0.59 Pg C yr−1 over the analysis period. From this estimate plus the most recent estimates for fossil fuel emissions and atmospheric CO2 accumulation, we infer a mean global land sink of −2.82 ± 0.85 Pg C yr−1 over the 1998 through 2011 period with strong interannual variation.

Gas Flow across Gaps in Protoplanetary Disks

Abstract: We analyze the gas accretion flow through a planet-produced gap in a protoplanetary disk. We adopt the α-disk model and ignore effects of planetary migration. We develop a semianalytic, one-dimensional model that accounts for the effects of the planet as a mass sink and also carry out two-dimensional hydrodynamic simulations of a planet embedded in a disk. The predictions of the mass flow rate through the gap based on the semianalytic model generally agree with the hydrodynamic simulations at the 25% level. Through these models, we are able to explore steady state disk structures and over large spatial ranges. The presence of an accreting ~1MJ planet significantly lowers the density of the disk within a region of several times the planet's orbital radius. The mass flow rate across the gap (and onto the central star) is typically 10%-25% of the mass accretion rate outside the orbit of the planet, for planet-to-star mass ratios that range from 5 × 10-5 to 1 × 10-3.

Methods for causality assessment of adverse drug reactions: a systematic review.

Abstract: Numerous methods for causality assessment of adverse drug reactions (ADRs) have been published The aim of this review is to provide an overview of these methods and discuss their strengths and weaknesses We conducted electronic searches in MEDLINE (via PubMed), EMBASE and the Cochrane databases to find all assessment methods Thirty-four different methods were found, falling into three broad categories: expert judgement/global introspection, algorithms and probabilistic methods (Bayesian approaches) Expert judgements are individual assessments based on previous knowledge and experience in the field using no standardized tool to arrive at conclusions regarding causality Algorithms are sets of specific questions with associated scores for calculating the likelihood of a cause-effect relationship Bayesian approaches use specific findings in a case to transform the prior estimate of probability into a posterior estimate of probability of drug causation The prior probability is calculated from epidemiological information and the posterior probability combines this background information with the evidence in the individual case to come up with an estimate of causation As a result of problems of reproducibility and validity, no single method is universally accepted Different causality categories are adopted in each method, and the categories are assessed using different criteria Because assessment methods are also not entirely devoid of individual judgements, inter-rater reliability can be low In conclusion, there is still no method universally accepted for causality assessment of ADRs

Balloon kyphoplasty in the management of vertebral compression fractures: an updated systematic review and meta-analysis.

Abstract: This systematic review updates the understanding of the evidence base for balloon kyphoplasty (BKP) in the management of vertebral compression fractures. Detailed searches of a number of electronic databases were performed from March to April 2006. Citation searches of included studies were undertaken and no language restrictions were applied. All controlled and uncontrolled studies were included with the exception of case reports. Prognostic factors responsible for pain relief and cement leakage were examined using meta-regression. Combined with previous evidence, a total of eight comparative studies (three against conventional medical therapy and five against vertebroplasty) and 35 case series were identified. The majority of studies were undertaken in older women with osteoporotic vertebral compression fractures with long-term pain that was refractory to medical treatment. In direct comparison to conventional medical management, patients undergoing BKP experienced superior improvements in pain, functionality, vertebral height and kyphotic angle at least up to 3-years postprocedure. Reductions in pain with BKP appeared to be greatest in patients with newer fractures. Uncontrolled studies suggest gains in health-related quality of life at 6 and 12-months following BKP. Although associated with a finite level of cement leakage, serious adverse events appear to be rare. Osteoporotic vertebral compression fractures appear to be associated with a higher level of cement leakage following BKP than non-osteoporotic vertebral compression fractures. In conclusion, there are now prospective studies of low bias, with follow-up of 12 months or more, which demonstrate balloon kyphoplasty to be more effective than medical management of osteoporotic vertebral compression fractures and as least as effective as vertebroplasty. Results from ongoing RCTs will provide further information in the near future.

Perceived autonomy support in physical education and leisure-time physical activity : A cross-cultural evaluation of the trans-contextual model

Abstract: This study tested the replicability and cross-cultural invariance of a trans-contextual model of motivation across 4 samples from diverse cultures. The model proposes a motivational sequence in which perceived autonomy support (PAS) in physical education (PE) predicts autonomous motivation, intentions, and behavior in a leisure-time (LT) physical activity context. High-school pupils from Britain, Greece, Poland, and Singapore completed measures of PAS and autonomous motives in a PE context. Goodfitting path-analytic models supported the main hypotheses of the trans-contextual model in the British, Greek, and Singaporean samples. PAS in PE had significant total effects on autonomous motives in LT, except in the Polish sample. The effect of autonomous motives in LT on physical activity intentions and behavior was mediated by theory of planned behavior constructs in all samples. Results supported the main hypotheses of the trans-contextual model across cultures, although the effect of PAS was not pervasive in the Polish sample.