4,989 research outputs found

    Interactions of C+(2PJ) with rare gas atoms: incipient chemical interactions, potentials and transport coefficients

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    Accurate interatomic potentials were calculated for the interaction of a singly charged carbon cation, C+, with a single rare gas atom, RG (RG = Ne–Xe). The RCCSD(T) method and basis sets of quadruple-ζ and quintuple-ζ quality were employed; each interaction energy was counterpoise corrected and extrapolated to the basis set limit. The lowest C+(2P) electronic term of the carbon cation was considered, and the interatomic potentials calculated for the diatomic terms that arise from these: 2Π and 2Σ+. Additionally, the interatomic potentials for the respective spin-orbit levels were calculated, and the effect on the spectroscopic parameters was examined. In doing this, anomalously large spin-orbit splittings for RG = Ar–Xe were found, and this was investigated using multi-reference configuration interaction calculations. The latter indicated a small amount of RG → C+ electron transfer and this was used to rationalize the observations. This is taken as evidence of an incipient chemical interaction, which was also examined via contour plots, Birge–Sponer plots and various population analyses across the C+-RG series (RG = He–Xe), with the latter showing unexpected results. Trends in several spectroscopic parameters were examined as a function of the increasing atomic number of the RG atom. Finally, each set of RCCSD(T) potentials was employed, including spin-orbit coupling to calculate the transport coefficients for C+ in RG, and the results were compared with the limited available data

    Prioritise safety, optimise success! Return to rugby postpartum

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    Pregnancy and childbirth involve substantial physical, physiological and psychological changes. As such, postpartum rugby players should be supported and appropriately prepared to return to the demands of rugby alongside the additional demands of motherhood. This review aims to discuss specific perinatal considerations that inform a rugby player's readiness to return-to-sport postpartum and present an approach to rehabilitation. Before engaging in full rugby training and matchplay, postpartum players should have progressed through the initial phases of rehabilitation and graded sports-specific training to prepare them for the loads they will be exposed to. Additional rehabilitation considerations include minimising deconditioning during pregnancy; medical concerns; the abdominal wall; the pelvic floor; perinatal breast changes, breastfeeding and risk of contact breast injury; body mass; nutritional requirements; hormonal considerations; athlete identity and psychological considerations; joining team training; return to contact and tackle training; evaluating player load tolerance and future research, policy and surveillance needs. A whole-systems, biopsychosocial approach following an evidence informed return-to-sport framework is recommended when rehabilitating postpartum rugby players. Health and exercise professionals are encouraged to use the perinatal-specific recommendations in this review to guide the development of postpartum rehabilitation protocols and resources

    Pharmacokinetics of TKM-130803 in Sierra Leonean patients with Ebola virus disease: plasma concentrations exceed target levels, with drug accumulation in the most severe patients

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    Background: TKM-130803 is a specific anti-EBOV therapeutic comprised of two small interfering RNAs (siRNA) siLpol-2 and siVP35-2. The pharmacokinetics (PK) of these siRNAs was defined in Ebola virus disease (EVD) patients, with reference to efficacy (ET) and toxicology thresholds (TT). The relationship between PK and patient survival was explored. Methods: Pharmacokinetic (PK) and pharmacodynamic (PD) data were available for seven participants with EVD in Sierra Leone who received 0·3 mg/kg of TKM-130803 by intravenous infusion over 2 h daily for up to 7 days. Plasma concentration of siRNA was compared to survival at 14 days. PK data were fitted to two-compartment models then Monte Carlo simulated PK profiles were compared to ET (Cmax 0·04–0·57 ng/mL and mean concentration 1·43 ng/mL), and TT (3000 ng/mL). Findings: Viral loads (VL) were not significantly different at treatment onset or during treatment (p = 0·1) in subjects who survived or died. siRNA was in quantitative excess of virus genomes throughout treatment, but the 95% percentile exceeded TT. The maximum AUC for which the 95% percentile remained under TT was a continuous infusion of 0·15 mg/kg/day. Plasma concentration of both siRNAs were higher in subjects who died compared to subjects who survived (p<0·025 both siRNAs). Interpretation: TKM-130803 was circulating in molar excess of circulating virus; a level considered needed for efficacy. Given extremely high viral loads it seems likely that the patients died because they were physiologically beyond the point of no return. Subjects who died exhibited some indication of impaired drug clearance, justifying caution in dosing strategies for such patients. This analysis has given a useful insight into the pharmacokinetics of the siRNA in the disease state and illustrates the value of designing PKPD studies into future clinical trials in epidemic situations. Funding: This work was supported by the Wellcome Trust of Great Britain (grant number 106491/Z/14/Z and 097997/Z/11/A) and by the EU FP7 project PREPARE (602525). The PHE laboratory was funded by the UK Department for International Development. The funders had no role in trial design, data collection or analysis. The views expressed are those of the authors and not necessarily those of Public Health England, the Department of Health, or the EU. Trial registration: Pan African Clinical Trials Registry PACTR201501000997429

    Implementing neuroimaging and eye tracking methods to assess neurocognitive development of young infants in low- and middle-income countries

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    Infants and children in low- and middle-income countries (LMICs) are frequently exposed to a range of environmental risk factors which may negatively affect their neurocognitive development. The mechanisms by which factors such as undernutrition and poverty impact development and cognitive outcomes in early childhood are poorly understood. This lack of knowledge is due in part to a paucity of objective assessment tools which can be implemented across different cultural settings and in very young infants. Over the last decade, technological advances, particularly in neuroimaging, have opened new avenues for research into the developing human brain, allowing us to investigate novel biological associations. This paper presents functional near-infrared spectroscopy (fNIRS), electroencephalography (EEG) and eye tracking (ET) as objective, cross-cultural methods for studying infant neurocognitive development in LMICs, and specifically their implementation in rural Gambia, West Africa. These measures are currently included, as part of a broader battery of assessments, in the Brain Imaging for Global Health (BRIGHT) project, which is developing brain function for age curves in Gambian and UK infants from birth to 24 months of age. The BRIGHT project combines fNIRS, EEG and ET with behavioural, growth, health and sociodemographic measures. The implementation of these measures in rural Gambia are discussed, including methodological and technical challenges that needed to be addressed to ensure successful data acquisition. The aim is to provide guidance to other groups seeking to implement similar methods in their research in other LMICs to better understand associations between environmental risk and early neurocognitive development

    La vie et la mort en peinture

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    L'abstraction visuelle ne constituerait pas d'abord une réflexion sur la nature du beau en soi, mais une approche cognitive renvoyant aux épistémologies et aux idéologies des époques où elle se manifeste. L'étude de différents discours tenus sur l'abstraction picturale au XIXe et au XXe siècles permet de suivre les valeurs attribuées à cette notion, notamment autour de l'opposition entre le vitalisme et la mort à partir des réflexions d'A. Riegl et W. Worringer. La différenciation entre l'abstrait et le concret, le sujet et l'objet se voit ainsi constamment relancée, dans la possibilité de leur réversibilité.Visual abstraction is not, at least not in the first place, a reflection upon the nature of beauty as such, but rather a cognitive approach to the world that bears witness to the epistemologies and ideologies of those periods of history where it appeared. The study of some of the discourses that have been held about pictural abstraction during the 19th and 20th centuries, notably the opposition between vitalism and death founded on the works of A. Riegl and W. Worringer, allows us to understand the various values that have been given to the notion. The distinction between abstraction and concreteness, subject and object, can here be seen, in regard to the possibility of their reversibility, as an ever-open question

    The absolute position of a resonance peak

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    It is common practice in scattering theory to correlate between the position of a resonance peak in the cross section and the real part of a complex energy of a pole of the scattering amplitude. In this work we show that the resonance peak position appears at the absolute value of the pole's complex energy rather than its real part. We further demonstrate that a local theory of resonances can still be used even in cases previously thought impossible

    The modern pollen-vegetation relationship of a tropical forest-savannah mosaic landscape, Ghana, West Africa

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    Transitions between forest and savannah vegetation types in fossil pollen records are often poorly understood due to over-production by taxa such as Poaceae and a lack of modern pollen-vegetation studies. Here, modern pollen assemblages from within a forest-savannah transition in West Africa are presented and compared, their characteristic taxa discussed, and implications for the fossil record considered. Fifteen artificial pollen traps were deployed for 1 year, to collect pollen rain from three vegetation plots within the forest-savannah transition in Ghana. High percentages of Poaceae and Melastomataceae/Combretaceae were recorded in all three plots. Erythrophleum suaveolens characterised the forest plot, Manilkara obovata the transition plot and Terminalia the savannah plot. The results indicate that Poaceae pollen influx rates provide the best representation of the forest-savannah gradient, and that a Poaceae abundance of >40% should be considered as indicative of savannah-type vegetation in the fossil record

    Latent cluster analysis of ALS phenotypes identifies prognostically differing groups

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    BACKGROUND Amyotrophic lateral sclerosis (ALS) is a degenerative disease predominantly affecting motor neurons and manifesting as several different phenotypes. Whether these phenotypes correspond to different underlying disease processes is unknown. We used latent cluster analysis to identify groupings of clinical variables in an objective and unbiased way to improve phenotyping for clinical and research purposes. METHODS Latent class cluster analysis was applied to a large database consisting of 1467 records of people with ALS, using discrete variables which can be readily determined at the first clinic appointment. The model was tested for clinical relevance by survival analysis of the phenotypic groupings using the Kaplan-Meier method. RESULTS The best model generated five distinct phenotypic classes that strongly predicted survival (p<0.0001). Eight variables were used for the latent class analysis, but a good estimate of the classification could be obtained using just two variables: site of first symptoms (bulbar or limb) and time from symptom onset to diagnosis (p<0.00001). CONCLUSION The five phenotypic classes identified using latent cluster analysis can predict prognosis. They could be used to stratify patients recruited into clinical trials and generating more homogeneous disease groups for genetic, proteomic and risk factor research
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