3,020 research outputs found
A combined field, laboratory and numerical study of the forces applied to, and the potential for removal of, bar top vegetation in a braided river
Vegetation can have an important role in controlling channel planform, through its effects on channel roughness, and root-reinforcement of bank and bar materials. Along the Platte River in central Nebraska, USA, The Platte River Recovery Implementation Program (PRRIP) has been tasked with managing the planform of the river to benefit endangered species. To investigate the potential use of planned Short Duration High Flow events (SDHFs) to manage bar vegetation, this study combined several approaches to determine whether flows of up to 227 m3s-1 through the central Platte River, could remove cottonwood, Phragmites and reed canarygrass stands of various ages and densities from in-channel bars. First, fieldwork was carried out to measure the uprooting resistance, and resistance to bending for each species. Second, a set of flume experiments was carried out to measure the forces exerted on the three species of interest under different flow conditions. Finally, a numerical study compared drag forces (driving) measured in the flume study, with uprooting forces (resisting) measured in the field, was carried out for each species to determine the likelihood of plant removal by SDHFs. Results showed that plants with more than a year of root growth, likely cannot be removed through drag and local scour alone, even at the 100-year recurrence interval discharge. At most, a few cottonwood seedlings could be removed from bars through drag, scour and undercutting, where rooting depths are still small. The results presented here help us further understand the positive feedbacks that lead to the creation of permanent, vegetated bars rather than mobile braided channels. As such, the findings could help inform management decisions for other braided rivers, and the combined field, flume and modelling techniques used in this study could be applied to other fluvial systems where vegetation and planform dynamics are of interest
First evidence of industrial fly-ash in an Antarctic ice core
Spheroidal carbonaceous particles (SCPs) are a component of fly-ash, the particulate by-product of industrial high temperature combustion of fuel-oil and coal-series fuels. We provide the first evidence that these indelible markers of industrialisation have been deposited in Antarctic ice, thousands of kilometres from any potential source. The earliest observed particle was deposited in an ice layer from 1936 CE. While depositional fluxes are low, chemical analysis of individual SCPs indicates a coal combustion origin
REDD+ on the rocks? Conflict over forest and politics of justice in Vietnam
In Vietnam, villagers involved in a REDD+ (reduced emissions from deforestation and forest degradation) pilot protect areas with rocks which have barely a tree on them. The apparent paradox indicates how actual practices differ from general ideas about REDD+ due to ongoing conflict over forest, and how contestations over the meaning of justice are a core element in negotiations over REDD+. We explore these politics of justice by examining how the actors involved in the REDD+ pilot negotiate the particular subjects, dimensions, and authority of justice considered relevant, and show how politics of justice are implicit to practical decisions in project implementation. Contestations over the meaning of justice are an important element in the practices and processes constituting REDD+ at global, national and local levels, challenging uniform definitions of forest justice and how forests ought to be managed
The influence of feeding behaviour and temperature on the capacity of mosquitoes to transmit malaria
Insecticide-treated bed nets reduce malaria transmission by limiting contact between mosquito vectors and human hosts when mosquitoes feed during the night. However, malaria vectors can also feed in the early evening and in the morning when people are not protected. Here, we explored how the timing of blood feeding interacts with environmental temperature to influence the capacity of Anopheles mosquitoes to transmit the human malaria parasite Plasmodium falciparum. In laboratory experiments, we found no effect of biting time itself on the proportion of mosquitoes that became infectious (vector competence) at constant temperature. However, when mosquitoes were maintained under more realistic fluctuating temperatures, there was a significant increase in competence for mosquitoes feeding in the evening (18:00), and a significant reduction in competence for those feeding in the morning (06:00), relative to those feeding at midnight (00:00). These effects appear to be due to thermal sensitivity of malaria parasites during the initial stages of parasite development within the mosquito, and the fact that mosquitoes feeding in the evening experience cooling temperatures during the night, whereas mosquitoes feeding in the morning quickly experience warming temperatures that are inhibitory to parasite establishment. A transmission dynamics model illustrates that such differences in competence could have important implications for malaria prevalence, the extent of transmission that persists in the presence of bed nets, and the epidemiological impact of behavioural resistance. These results indicate that the interaction of temperature and feeding behaviour could be a major ecological determinant of the vectorial capacity of malaria mosquitoes
Toxic metal enrichment and boating intensity: sediment records of antifoulant copper in shallow lakes of eastern England
Tributyltin (TBT), an aqueous biocide derived from antifouling paint pollution, is known to have impacted coastal marine ecosystems, and has been reported in the sediment of the Norfolk and Suffolk Broads, a network of rivers and shallow lakes in eastern England. In the marine environment, the 1987 TBT ban has resulted in expanded use of alternative biocides, raising the question of whether these products too have impacted the Broads ecosystem and freshwaters in general. Here we examine the lake sediment record in the Norfolk and Suffolk Broads for contamination by copper (Cu) (as an active biocide agent) and zinc (Zn) (as a component of booster biocides), to assess their occurrence and potential for causing environmental harm in freshwater ecosystems. We find that, after the introduction of leisure boating, there is a statistically significant difference in Cu enrichment between heavily and lightly boated sites, while no such difference exists prior to this time. At the heavily boated sites the onset of Cu enrichment coincides with a period of rapid increase in leisure boating. Such enrichment is maintained to the present day, with some evidence of continued increase. We conclude that Cu-based antifouling has measurably contaminated lakes exposed to boating, at concentrations high enough to cause ecological harm. Similar findings can be expected at other boated freshwater ecosystems elsewhere in the world
High accuracy theoretical investigations of CaF, SrF, and BaF and implications for laser-cooling
The NL-eEDM collaboration is building an experimental setup to search for the
permanent electric dipole moment of the electron in a slow beam of cold barium
fluoride molecules [Eur. Phys. J. D, 72, 197 (2018)]. Knowledge of molecular
properties of BaF is thus needed to plan the measurements and in particular to
determine an optimal laser-cooling scheme. Accurate and reliable theoretical
predictions of these properties require incorporation of both high-order
correlation and relativistic effects in the calculations. In this work
theoretical investigations of the ground and the lowest excited states of BaF
and its lighter homologues, CaF and SrF, are carried out in the framework of
the relativistic Fock-space coupled cluster (FSCC) and multireference
configuration interaction (MRCI) methods. Using the calculated molecular
properties, we determine the Franck-Condon factors (FCFs) for the transition, which was successfully used for
cooling CaF and SrF and is now considered for BaF. For all three species, the
FCFs are found to be highly diagonal. Calculations are also performed for the
transition recently
exploited for laser-cooling of CaF; it is shown that this transition is not
suitable for laser-cooling of BaF, due to the non-diagonal nature of the FCFs
in this system. Special attention is given to the properties of the
state, which in the case of BaF causes a leak channel, in contrast
to CaF and SrF species where this state is energetically above the excited
states used in laser-cooling. We also present the dipole moments of the ground
and the excited states of the three molecules and the transition dipole moments
(TDMs) between the different states.Comment: Minor changes; The following article has been submitted to the
Journal of Chemical Physics. After it is published, it will be found at
https://publishing.aip.org/resources/librarians/products/journals
Recruitment of ethnic minority patients to a cardiac rehabilitation trial: The Birmingham Rehabilitation Uptake Maximisation (BRUM) study [ISRCTN72884263]
Background: Concerns have been raised about low participation rates of people from minority ethnic groups
in clinical trials. However, the evidence is unclear as many studies do not report the ethnicity of participants and
there is insufficient information about the reasons for ineligibility by ethnic group. Where there are data, there
remains the key question as to whether ethnic minorities more likely to be ineligible (e.g. due to language) or
decline to participate. We have addressed these questions in relation to the Birmingham Rehabilitation Uptake
Maximisation (BRUM) study, a randomized controlled trial (RCT) comparing a home-based with a hospital-based
cardiac rehabilitation programme in a multi-ethnic population in the UK.
Methods: Analysis of the ethnicity, age and sex of presenting and recruited subjects for a trial of cardiac
rehabilitation in the West-Midlands, UK.
Participants: 1997 patients presenting post-myocardial infarction, percutaneous transluminal coronary angioplasty
or coronary artery bypass graft surgery.
Data collected: exclusion rates, reasons for exclusion and reasons for declining to participate in the trial by ethnic
group.
Results: Significantly more patients of South Asian ethnicity were excluded (52% of 'South Asian' v 36% 'White
European' and 36% 'Other', p < 0.001). This difference in eligibility was primarily due to exclusion on the basis of
language (i.e. the inability to speak English or Punjabi). Of those eligible, similar proportions were recruited from
the different ethnic groups (white, South Asian and other). There was a marked difference in eligibility between
people of Indian, Pakistani or Bangladeshi origin
Managing Opioid Withdrawal Symptoms During the Fentanyl Crisis: A Review
Andrea Nicole Weber,1 Joshua Trebach,2 Marielle A Brenner,2 Mary Margaret Thomas,3 Nicholas L Bormann4 1Department of Psychiatry, University of Iowa, Iowa City, IA, USA; 2Department of Emergency Medicine, University of Iowa, Iowa City, IA, USA; 3Hardin Library for the Health Sciences, University of Iowa, Iowa City, IA, USA; 4Department of Psychiatry and Psychology, Mayo Clinic, Rochester, MN, USACorrespondence: Andrea Nicole Weber, Department of Psychiatry, University of Iowa, 500 Newton Road, 1-308 MEB, Iowa City, IA, 52242, USA, Tel +1-319-335-6980, Fax +1-319-384-7467, Email [email protected]: Illicitly manufactured fentanyl (IMF) is a significant contributor to the increasing rates of overdose-related deaths. Its high potency and lipophilicity can complicate opioid withdrawal syndromes (OWS) and the subsequent management of opioid use disorder (OUD). This scoping review aimed to collate the current OWS management of study populations seeking treatment for OWS and/or OUD directly from an unregulated opioid supply, such as IMF. Therefore, the focus was on therapeutic interventions published between January 2010 and November 2023, overlapping with the period of increasing IMF exposure. A health science librarian conducted a systematic search on November 13, 2023. A total of 426 studies were screened, and 173 studies were reviewed at the full-text level. Forty-nine studies met the inclusion criteria. Buprenorphine and naltrexone were included in most studies with the goal of transitioning to a long-acting injectable version. Various augmenting agents were tested (buspirone, memantine, suvorexant, gabapentin, and pregabalin); however, the liberal use of adjunctive medication and shortened timelines to initiation had the most consistently positive results. Outside of FDA-approved medications for OUD, lofexidine, gabapentin, and suvorexant have limited evidence for augmenting opioid agonist initiation. Trials often have low retention rates, particularly when opioid agonist washout is required. Neurostimulation strategies were promising; however, they were developed and studied early. Precipitated withdrawal is a concern; however, the rates were low and adequately mitigated or managed with low- or high-dose buprenorphine induction. Maintenance treatment continues to be superior to detoxification without continued management. Shorter induction protocols allow patients to initiate evidence-based treatment more quickly, reducing the use of illicit or non-prescribed substances.Keywords: synthetic opioids, treatment, diagnosis, prevention, addiction medicin
Behavior of QQ-Plots and Genomic Control in Studies of Gene-Environment Interaction
Genome-wide association studies of gene-environment interaction (GxE GWAS) are becoming popular. As with main effects GWAS, quantile-quantile plots (QQ-plots) and Genomic Control are being used to assess and correct for population substructure. However, in GE work these approaches can be seriously misleading, as we illustrate; QQ-plots may give strong indications of substructure when absolutely none is present. Using simulation and theory, we show how and why spurious QQ-plot inflation occurs in GE GWAS, and how this differs from main-effects analyses. We also explain how simple adjustments to standard regression-based methods used in GE GWAS can alleviate this problem
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