2,040 research outputs found
The Amazon River Basin as an Analog for the Pre-Ice Age Bell River Basin of North America
The pre-ice age Bell River basin of North America was comparable in size to the modern day Amazon basin of South America. In Miocene time, it drained most of Canada and one third of the North American continent before being defeated by tectonics, volcanism, and glaciation. Beginning about 2.5 million years ago, continental glaciers re-routed the paths of the tributaries in Canada, leaving behind only traces of this once massive river basin in headwater valleys in the Rocky Mountains and in a giant river delta in the Labrador Sea. The contemporary Amazon River basin provides an analog for estimating fluvial parameters of the ancient Bell River system. Both systems had headwaters in high mountains and canyons, then drained across flat, continental-scale basins, and emptied into the Atlantic Ocean through broad continental rift zones. Both have large deltas and long submarine turbidity channels. Comparing the Amazon\u27s delta, tributaries, stream gradients, and sediment loads to the remnants of the Bell River system could support a model for pre-ice age North American drainage. This could then augment studies of tectonic displacements in the western interior, for example, uplift of the Great Plains and Rocky Mountains, effects of Yellowstone volcanism, and faulting in the Great Basin
Sensitivity of Prescribing High-Intensity, Interval Training Using the Critical Power Concept
International Journal of Exercise Science 8(3): 202-212, 2015. The critical power (CP) concept enables the calculation of time to exhaustion (tLIM) for a given power output above CP using the equation of tLIM = W’/(power – CP), where W’ is the curvature constant, and CP is the asymptote for the power-tLIM relationship. The CP concept offers great promise for prescribing high-intensity interval training (HIIT); however, knowledge on the concept’s sensitivity is lacking (i.e., how much of a difference in W’ expenditure is needed to evoke different metabolic responses). We tested if two different power-tLIM configurations expending identical proportions of W’ would evoke different end-exercise oxygen uptake (VO2) and heart rate (HR) values. Five men and five women completed a graded exercise test, 3-min all-out exercise tests, and intervals prescribed to deplete either 70 or 80% of W’ on separate visits. Consistency statistics of intraclass correlation (ICC a), standard error of measure (SEM), and coefficient of variation (CV) were calculated on end-exercise values. End-exercise VO2 were similar for the 3.5- and 5-min bouts, depleting 70% of W’ (ICC a = 0.91, SEM = 3.23 mL·kg-1·min-1, CV = 8.1%) and similar for the 4- and 5-min bouts, depleting 80% of W’ (ICC a = 0.95, SEM = 2.34 mL·kg-1·min-1, CV = 8.1%). No VO2 differences were observed between trials or conditions (p = 0.58). Similarly, HR values (~181 b·min-1) did not differ between trials or conditions (p = 0.45). Use of the CP concept for HIIT prescriptions of different power-tLIM configurations evokes similar end-exercise VO2 values on a given day. Our findings indicate that \u3e10% W’ depletion is necessary to evoke different metabolic responses to HIIT
Serum p53 antibodies: predictors of survival in small-cell lung cancer?
Serum p53 antibodies have been shown to be a poor prognostic marker in resected non-small-cell lung cancer (NSCLC), but studies in small-cell lung cancer (SCLC) have been contradictory. We have studied the incidence of p53 antibodies in a large SCLC cohort treated at one oncology centre and correlated the results with survival. 231 patients (63% male, median age 65), diagnosed and treated for SCLC between 1987 and 1994 at The Royal Marsden Hospital NHS Trust, had sera stored pretreatment. All samples were tested for p53 antibodies (p53-Ab) using a standardized ELISA technique with a selection of strongly ELISA positive, weakly ELISA positive and negative samples being confirmed with immunoprecipitation. 54 patients were positive for p53-Ab (23%). The presence of a high titre of p53-Ab (titre ratio >5) appears to be associated with a survival advantage with a relative risk of death of 1.71 (95% CI: 1.14–2.58) in those without the antibody (P = 0.02). This study, the largest homogenous group so far looking at p53-Ab in SCLC, suggests that p53 antibody detection may have a role in predicting outcome in this type of cancer. © 2000 Cancer Research Campaign http://www.bjcancer.co
The psychological impact of dependency in adults withchronic fatigue syndrome/myalgic encephalomyelitis: A qualitative exploration
Chronic fatigue syndrome/myalgic encephalomyelitis can limit functional capacity, producing various degrees of disability and psychological distress. Semi-structured interviews explored the experiences of adults with chronic fatigue syndrome/myalgic encephalomyelitis being physically dependent on other people for help in daily life, and whether physical dependency affects their psychological well-being. Thematic analysis generated six themes: loss of independence and self-identity, an invisible illness, anxieties of today and the future, catch-22, internalised anger, and acceptance of the condition. The findings provide insight into the psychological impact of dependency. Implications for intervention include better education relating to chronic fatigue syndrome/myalgic encephalomyelitis for family members, carers, and friends; ways to communicate their needs to others who may not understand chronic fatigue syndrome/myalgic encephalomyelitis; and awareness that acceptance of the condition could improve psychological well-being
Disseminated Effects in Agent Based Models: A Potential Outcomes Framework and Application to Inform Pre-Exposure Prophylaxis Coverage Levels for HIV Prevention
Pre-exposure prophylaxis (PrEP) for HIV prevention may not only benefit the individual who uses it, but also their uninfected sexual risk contacts. We developed an agent-based model using a novel trial emulation approach to quantify disseminated effects of PrEP use among men who have sex with men in Atlanta, USA from 2015 to 2017. Components (subsets of agents connected through partnerships in a sexual network, but not sharing partnerships with any other agents) were first randomized to an intervention coverage level or control, then within intervention components, eligible agents were randomized to PrEP. We estimated direct and disseminated (indirect) effects using randomization-based estimators and reported corresponding 95% simulation intervals across scenarios ranging from 10% to 90% coverage in the intervention components. A population of 11,245 agents was simulated with an average of 1,551 components identified. Comparing agents randomized to PrEP in 70% coverage components to control agents, there was a 15% disseminated risk reduction in HIV incidence (95% simulation intervals = 0.65, 1.05). Individuals not on PrEP may receive a protective benefit by being in a sexual network with higher PrEP coverage. Agent-based models are useful to evaluate possible direct and disseminated effects of HIV prevention modalities in sexual networks
Optimising mechanical separation of anaerobic digestate for total solids and nutrient removal
Publication history: Accepted - 16 June 2023; Published - 28 June 2023.Mechanical separation of anaerobic digestate has been identified as a method to reduce pollution risk to waterways by partitioning phosphorus in the solid fraction and reducing its application to land. Separators have adjustable parameters which affect separation efficiency, and hence the degree of phosphorous partitioning, but information on how these parameters affect separation performance is limited in the literature. Two well known technologies were investigated, decanter centrifuge and screw press, to determine the most efficient method of separation. Counterweight load and the use of an oscillator were adjusted for the screw press, while bowl speed, auger differential speed, feed rate and polymer addition were modified for the decanter centrifuge. Separation efficiency was determined for total solids, phosphorus, nitrogen, potassium, and carbon, and the total solids
content of resulting fractions was measured. The decanter centrifuge had higher separation efficiency for phosphorus in all cases, ranging from 51% to 71.5%, while the screw press had a phosphorus separation efficiency
ranging from 8.5% to 10.9% for digestate of ~5% solids (slurry/grass silage mix). Separation by decanter centrifuge partitioned up to 56% of nitrogen in the solid fraction leaving a reduced nitrogen content in the liquid fraction available for land spreading; this nitrogen would most likely need to be replaced by chemical fertiliser which would add to the cost of the system. The decanter centrifuge is better suited to cases where phosphorus recovery is the most important factor, while the screw press could be advantageous in cases where cost is a limiting factor.This project was supported by The Bryden Centre. The Bryden Centre project is supported by the European Union’s INTERREG VA Programme, managed by the Special EU Programmes Body (SEUPB). The
views and opinions expressed in this paper do not necessarily reflect those of the European Commission or the Special EU Programmes Body (SEUPB). The work was also supported by Queen’s University Belfast and the Agri-Food and Biosciences Institute in Northern Ireland
An economic analysis of anaerobic digestate fuel pellet production: can digestate fuel pellets add value to existing operations?
Publication history: Accepted - 9 April 2021; Published online - 16 April 2021.Anaerobic digestion provides renewable energy through waste valorisation, but the digestate by-product is
underutilised and presents a risk to water quality. Mechanical separation partitions phosphorous into the solid
fraction and further processing into a fuel pellet can provide an additional source of energy and revenue. Previous
economic analyses looked only at aspects of the system (e.g. operational costs solely) and the system requires
further investigation to determine viability. In this paper, an economic assessment of digestate fuel pellet production
at farm-scale anaerobic digestion plants was carried out. The significance of this work is to provide a
comprehensive assessment of the energy, phosphorous, and economic balances involved in digestate fuel pellet
production at existing anaerobic digestion plants. The aim of this paper is to determine the financial viability of
digestate fuel pellet production with objectives to compare two mechanical separation technologies: screw press,
and decanting centrifuge. Economies of scale hold true for digestate pellet production and the available digestate
in typical UK farm-based anaerobic digestion plants ( 500 kWe) is insufficient for profitability, with pellet
production costing from £176/t (decanting centrifuge) to £215/t (screw press), compared to a typical wood pellet
sale price of £185/t. Increasing digestate quantity by collaboration of plant operators can reduce the cost of pellet
production to between £95/t and £121/t, improving financial viability and increasing the profit per head of cattle
by 9–20% on a typical dairy farm utilising anaerobic digestion. The system has potential to aid rural development
while also protecting the environment and contributing to the diversification of energy supply.This project was supported by The Bryden Centre. The Bryden Centre
project is supported by the European Union’s INTERREG VA Programme,
managed by the Special EU Programmes Body (SEUPB). The views and
opinions expressed in this paper do not necessarily reflect those of the
European Commission or the Special EU Programmes Body (SEUPB). The
work was also supported by Queen’s University Belfast and the Agri-Food
and Biosciences Institute in Northern Ireland
Effect of anaerobic digestate fuel pellet production on Enterobacteriaceae and Salmonella persistence
Publication history: Accepted - 10 June 2022; Published online - 7 July 2022.Production of digestate pellets for fuel has been identified as a promising circular
economy approach to provide renewable energy and additional income to
farms, while at the same time presenting the potential to divert raw digestate
from nutrient-saturated
land and reduce the risk to water quality. Although
previous research has investigated the feasibility of pellet production, there
has been little focus on the bio-safety
aspects of the system. Little is currently
known about the persistence of bacteria present in the digestate and the potential
impacts on human health for those handling this product. The aim of
the present research was to determine the effect that each step in the pellet
production process has on bacteria numbers: anaerobic digestion, mechanical
separation, solid drying, and pelletisation. Enterobacteriaceae enumeration
by colony count method was used to quantify bacteria, and the presence of
Salmonella at each stage was determined. The Enterobacteriaceae count reduced
with each stage, and the final pelletisation step reduced bacteria numbers
to below detectable levels (<10 colony forming units/g). Salmonella was
only detected in the starting slurry and absent from digestate onwards. Storage
of the pellets under winter and simulated summer conditions showed no reactivation
of Enterobacteriaceae over time. The pelletisation process produces a
digestate product with Enterobacteriaceae counts below the maximum threshold
(PAS110 specification) for transport off the source farm, but care must still
be taken when handling digestate pellets as complete sterilisation has not been
confirmed.This project was supported by The Bryden Centre. The
Bryden Centre project is supported by the European
Union's INTERREG VA Programme, managed by the
Special EU Programmes Body (SEUPB).
The work was also supported
by Queen's University Belfast and the Agri-Food
and Biosciences Institute in Northern Ireland
Transcranial Magnetic Stimulation for Post-traumatic Stress Disorder
Post-traumatic stress disorder (PTSD) is a psychiatric disorder that causes significant functional impairment and is related to altered stress response and reinforced learned fear behavior. PTSD has been found to impact three functional networks in the brain: default mode, executive control, and salience. The executive control network includes the dorsolateral prefrontal cortex (DLPFC) and lateral PPC. The salience network involves the anterior cingulate cortex, anterior insula, and amygdala. This latter network has been found to have increased functional connectivity in PTSD. Transcranial Magnetic Stimulation (TMS) is a technique used in treating PTSD and involves stimulating specific portions of the brain through electromagnetic induction. Currently, high-frequency TMS applied to the left dorsolateral prefrontal cortex (DLPFC) is approved for use in treating major depressive disorder (MDD) in patients who have failed at least one medication trial. In current studies, high-frequency stimulation has been shown to be more effective in PTSD rating scales posttreatment than low-frequency stimulation. The most common side effect is headache and scalp pain treated by mild analgesics. Seizures are a rare side effect and are usually due to predisposing factors. Studies have been done to assess the overall efficacy of TMS. However, results have been conflicting, and sample sizes were small. More research should be done with larger sample sizes to test the efficacy of TMS in the treatment of PTSD. Overall, TMS is a relatively safe treatment. Currently, the only FDA- approved to treat refractory depression, but with the potential to treat many other conditions
Landscape drivers of genomic diversity and divergence in woodland Eucalyptus
Spatial genetic patterns are influenced by numerous factors, and they can vary even among coexisting, closely related species due to differences in dispersal and selection. Eucalyptus (L'Héritier 1789; the "eucalypts") are foundation tree species that provide essential habitat and modulate ecosystem services throughout Australia. Here we present a study of landscape genomic variation in two woodland eucalypt species, using whole-genome sequencing of 388 individuals of Eucalyptus albens and Eucalyptus sideroxylon. We found exceptionally high genetic diversity (π ≈ 0.05) and low genome-wide, interspecific differentiation (FST = 0.15) and intraspecific differentiation between localities (FST ≈ 0.01-0.02). We found no support for strong, discrete population structure, but found substantial support for isolation by geographic distance (IBD) in both species. Using generalized dissimilarity modelling, we identified additional isolation by environment (IBE). Eucalyptus albens showed moderate IBD, and environmental variables have a small but significant amount of additional predictive power (i.e. IBE). Eucalyptus sideroxylon showed much stronger IBD and moderate IBE. These results highlight the vast adaptive potential of these species and set the stage for testing evolutionary hypotheses of interspecific adaptive differentiation across environments
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