Vortex Erosion in a Shallow Water Model of the Polar Vortex

This is the author accepted manuscript. The final version is available from Elsevier via the DOI in this record.The erosion of a model stratospheric polar vortex in response to bottom boundary forcing is investigated numerically. Stripping of filaments of air from the polar vortex has been implicated in the occurrence of stratospheric sudden warmings (SSWs) but it is not understood in detail what factors determine the rate and amount of stripping. Here a shallow water vortex forced by topography is used to investigate the factors initiating stripping and whether this leads the vortex to undergo an SSW. It is found that the amplitude of topographic forcing must exceed some threshold (of order 200–450 m) in order for significant stripping to occur. For larger forcing amplitudes significant stripping occurs, but not as an instantaneous response to the forcing; rather, the forcing appears to initiate a process that ultimately results in stripping several tens of days later. There appears to be no simple quantitative relationship between the amount of mass stripped and the topography amplitude. However, at least over the early stages of the experiments, there is a good correlation between the amount of mass stripped and the global integral of wave activity, which may be interpreted as a measure of the accumulated topographic forcing. Finally there does not appear to be a simple correspondence between amount of mass stripped and the occurrence of an SSW.Robin Beaumont was supported during this research with a PhD studentship funded by an EPSRC Doctoral Training Grant

Vortex dynamics of stratospheric sudden warmings: a reanalysis data study using PV contour integral diagnostics

This is the author accepted manuscript. The final version is available from Wiley via the DOI in this record.ERA‐40 reanalysis dataset produced by the European Centre for Medium‐Range Weather Forecasts (ECMWF) and provided by the British Atmospheric Data Centre (BADC).The dynamics of the polar vortex underlying stratospheric sudden warming (SSW) events are investigated in a data-based diagnostic study. Potential vorticity (PV) contour integral quantities on isentropic surfaces are discussed in a unified framework; new expressions for their time evolution, particularly suitable for evaluation from data, are presented and related to previous work. Diagnostics of mass and circulation are calculated from ERA-40 reanalysis data for the stratosphere in case-studies of seven winters with different SSW behaviour. The edge of the polar vortex is easily identifiable in these diagnostics as an abrupt transition from high to low gradients of PV, and the warming events are clearly visible. The amount of air stripped from the vortex as part of a preconditioning leading up to the warming events is determined using the balance equation of the mass integral. Significant persistent removal of mass from the vortex is found, with several such stripping events identifiable throughout the winter, especially in those during which a major sudden warming event occurred. These stripping episodes are visible in corresponding PV maps, where tongues of high PV are being stripped from the vortex and mixed into the surrounding surf zone. An attempt is made to diagnose from the balance equation of the circulation the effect of frictional forces such as gravity wave dissipation on the polar vortex.EPSR

The “weanling’s dilemma” revisited: Evolving bodies of evidence and the problem of infant paleodietary interpretation

Breastfeeding is known to be a powerful mediator of maternal and childhood health, with impacts throughout the lifecourse. Paleodietary studies of the past thirty years have accordingly taken an enduring interest in the health and diet of young children as a potential indicator of population fertility, subsistence, and mortality patterns. While progress has been made in recent decades towards acknowledging the agency of children, many paleodietary reconstructions have failed to incorporate developments in cognate disciplines revealing synergistic dynamics between maternal and offspring biology. Central to this understanding has been heavy reliance on the “weanling’s dilemma”, in which infants are thought to face a bleak choice between loss of immunity or malnutrition. Using a review of immunological and epidemiological evidence for the dynamic and supportive role that breastfeeding plays throughout the complementary feeding period, this paper offers context and nuance for understanding past feeding transitions. We suggest that future interpretative frameworks for infant paleodietary and bioarchaeological research should include a broad knowledge base that keeps pace with relevant developments outside of those disciplines

Continental-scale patterns of pathogen prevalence: a case study on the corncrake

Pathogen infections can represent a substantial threat to wild populations, especially those already limited in size. To determine how much variation in the pathogens observed among fragmented populations is caused by ecological factors, one needs to examine systems where host genetic diversity is consistent among the populations, thus controlling for any potentially confounding genetic effects. Here, we report geographic variation in haemosporidian infection among European populations of corncrake. This species now occurs in fragmented populations, but there is little genetic structure and equally high levels of genetic diversity among these populations. We observed a longitudinal gradient of prevalence from western to Eastern Europe negatively correlated with national agricultural yield, but positively correlated with corncrake census population sizes when only the most widespread lineage is considered. This likely reveals a possible impact of local agriculture intensity, which reduced host population densities in Western Europe and, potentially, insect vector abundance, thus reducing the transmission of pathogens. We conclude that in the corncrake system, where metapopulation dynamics resulted in variations in local census population sizes, but not in the genetic impoverishment of these populations, anthropogenic activity has led to a reduction in host populations and pathogen prevalence

Turnitin said it wasn't happy: Can the regulatory discourse of plagiarism detection operate as a change artefact for writing development?

This paper centres on the tensions between the introduction of plagiarism detection software (Turnitin) for student and tutor use at undergraduate level and the aim to promote a developmental approach to writing for assessment at a UK university. Aims to promote developmental models for writing often aim to counteract the effects of the structural organisation of learning and assessment in higher education. This paper will discuss the potential for the implementation of plagiarism detection software to operate as a 'change artefact', creating opportunities for a departure from the habits of practice created by the demands of writing for assessment and the potential for the emergence of enclaves of good practice in respect of writing development. Tutor and student qualitative responses, gathered via questionnaires and focus groups were analysed in order to investigate the effectiveness of this initiative. In this inquiry plagiarism detection emerges as a dominant theme within regulatory discourses of malpractice in higher education. The promotion of writing development via a tool for regulation and plagiarism detection seems to be a mismatch and the extent to which Turnitin can be operate as a change artefact to promote developmental approaches to writing for assessment in higher education is questioned. The suitability of plagiarism detection software as a tool to promote writing development will be discussed in light of the findings from this inquiry

European wildcat populations are subdivided into five main biogeographic groups: consequences of Pleistocene climate changes or recent anthropogenic fragmentation?

Extant populations of the European wildcat are fragmented across the continent, the likely consequence of recent extirpations due to habitat loss and over-hunting. However, their underlying phylogeographic history has never been reconstructed. For testing the hypothesis that the European wildcat survived the Ice Age fragmented in Mediterranean refuges, we assayed the genetic variation at 31 microsatellites in 668 presumptive European wildcats sampled in 15 European countries. Moreover, to evaluate the extent of subspecies/population divergence and identify eventual wild × domestic cat hybrids, we genotyped 26 African wildcats from Sardinia and North Africa and 294 random-bred domestic cats. Results of multivariate analyses and Bayesian clustering confirmed that the European wild and the domestic cats (plus the African wildcats) belong to two well-differentiated clusters (average Ф ST = 0.159, r st = 0.392, P > 0.001; Analysis of molecular variance [AMOVA]). We identified from c. 5% to 10% cryptic hybrids in southern and central European populations. In contrast, wild-living cats in Hungary and Scotland showed deep signatures of genetic admixture and introgression with domestic cats. The European wildcats are subdivided into five main genetic clusters (average Ф ST = 0.103, r st = 0.143, P > 0.001; AMOVA) corresponding to five biogeographic groups, respectively, distributed in the Iberian Peninsula, central Europe, central Germany, Italian Peninsula and the island of Sicily, and in north-eastern Italy and northern Balkan regions (Dinaric Alps). Approximate Bayesian Computation simulations supported late Pleistocene-early Holocene population splittings (from c. 60 k to 10 k years ago), contemporary to the last Ice Age climatic changes. These results provide evidences for wildcat Mediterranean refuges in southwestern Europe, but the evolution history of eastern wildcat populations remains to be clarified. Historical genetic subdivisions suggest conservation strategies aimed at enhancing gene flow through the restoration of ecological corridors within each biogeographic units. Concomitantly, the risk of hybridization with free-ranging domestic cats along corridor edges should be carefully monitored

A new method for tracking of motor skill learning through practical application of Fitts’ law

This article is made available through the Brunel Open Access Publishing Fund.A novel upper limb motor skill measure, task productivity rate (TPR) was developed integrating speed and spatial error, delivered by a practical motor skill rehabilitation task (MSRT). This prototype task involved placement of 5 short pegs horizontally on a spatially configured rail array. The stability of TPR was tested on 18 healthy right-handed adults (10 women, 8 men, median age 29 years) in a prospective single-session quantitative within-subjects study design. Manipulations of movement rate 10% faster and slower relative to normative states did not significantly affect TPR, F(1.387, 25.009) = 2.465, p = .121. A significant linear association between completion time and error was highest during the normative state condition (Pearson's r = .455, p < .05). Findings provided evidence that improvements in TPR over time reflected motor learning with possible changes in coregulation behavior underlying practice under different conditions. These findings extend Fitts’ law theory to tracking of practical motor skill using a dexterity task, which could have potential clinical applications in rehabilitation

Synovial inflammation in an experimental model of metabolic syndrome in the rabbit

Objetivo: Analizar el efecto del síndrome metabólico (SM) sobre la inflamación sinovial en un modelo experimental en conejo. Material y métodos: Se probaron tres intervenciones dietéticas diferentes para inducir un modelo experimental de SM, en 21 conejos New Zealand hembra, de 8 meses de edad: 1) alimentación con dieta enriquecida con 1% de colesterol y 3% de aceite de cacahuete y agua ad libitum; 2) alimentación con dieta normal y agua con 30% de fructosa ad libitum; 3) alimentación con dieta enriquecida con 1% de colesterol y 3% de aceite de cacahuete y agua con 30% de fructosa ad limitum. Los animales se dejaron evolucionar durante 12 semanas y se hizo un seguimiento semanal de peso, glucosa basal, colesterol HDL, triglicéridos. Tras el sacrificio, se tomaron muestras de membrana sinovial para cuantificar el infiltrado macrofágico sinovial mediante inmunohistoquímica. Resultados: La única intervención dietética con la que conseguimos inducir alteraciones asociadas al SM en los conejos fue alimentándolos con una dieta hiperlipémica. Estos animales, además de presentar hiperglucemia y dislipemia, tenían un infiltrado macrofágico sinovial mayor que el del grupo control. Conclusión: La alimentación con dieta hiperlipémica induce alteraciones típicas del SM en el conejo, acompañadas de un aumento del infiltrado macrofágico sinovial, lo que sugiere que el macrófago podría desempeñar un papel importante en el inicio y/o la progresión de la artrosis descrita que se asocia con el SMObjetive: To analyze the effect of metabolic syndrome (MS) upon synovial inflammation in an experimental model in the rabbit. Material and methodology: Three different diets were used to induce an experimental model of MS in 21 female New Zealand rabbits (aged 8 months): 1) diet enriched with 1% cholesterol and 3% peanut oil, with water, ad libitum; 2) normal diet, with water, and 30% fructose, ad libitum; 3) diet enriched with 1% cholesterol and 3% peanut oil, with water, and 30% fructose, ad libitum. The animals were followed-up on for 12 weeks, with weekly monitoring of body weight, basal glucose, HDL-cholesterol and triglycerides. Following sacrifice, synovial membrane samples were collected to quantify the synovial macrophage infiltrate using immunohistochemical techniques. Results: The only diet to induce alterations associated with MS in the rabbits was the hyperlipidemic diet. These animals, in addition to presenting hyperglycemia and dyslipidemia, showed greater synovial macrophage infiltration than the control group. Conclusion: A hyperlipidemic diet induces alterations typical of MS in the rabbit, accompanied by an increase in synovial macrophage infiltrationEsta investigación ha sido financiada por FUNDACIÓN MAPFR