Ice formation and development in aged, wintertime cumulus over the UK: observations and modelling

In situ high resolution aircraft measurements of cloud microphysical properties were made in coordination with ground based remote sensing observations of a line of small cumulus clouds, using Radar and Lidar, as part of the Aerosol Properties, PRocesses And InfluenceS on the Earth's climate (APPRAISE) project. A narrow but extensive line (~100 km long) of shallow convective clouds over the southern UK was studied. Cloud top temperatures were observed to be higher than −8 °C, but the clouds were seen to consist of supercooled droplets and varying concentrations of ice particles. No ice particles were observed to be falling into the cloud tops from above. Current parameterisations of ice nuclei (IN) numbers predict too few particles will be active as ice nuclei to account for ice particle concentrations at the observed, near cloud top, temperatures (−7.5 °C). The role of mineral dust particles, consistent with concentrations observed near the surface, acting as high temperature IN is considered important in this case. It was found that very high concentrations of ice particles (up to 100 L−1) could be produced by secondary ice particle production providing the observed small amount of primary ice (about 0.01 L−1) was present to initiate it. This emphasises the need to understand primary ice formation in slightly supercooled clouds. It is shown using simple calculations that the Hallett-Mossop process (HM) is the likely source of the secondary ice. Model simulations of the case study were performed with the Aerosol Cloud and Precipitation Interactions Model (ACPIM). These parcel model investigations confirmed the HM process to be a very important mechanism for producing the observed high ice concentrations. A key step in generating the high concentrations was the process of collision and coalescence of rain drops, which once formed fell rapidly through the cloud, collecting ice particles which caused them to freeze and form instant large riming particles. The broadening of the droplet size-distribution by collision-coalescence was, therefore, a vital step in this process as this was required to generate the large number of ice crystals observed in the time available. Simulations were also performed with the WRF (Weather, Research and Forecasting) model. The results showed that while HM does act to increase the mass and number concentration of ice particles in these model simulations it was not found to be critical for the formation of precipitation. However, the WRF simulations produced a cloud top that was too cold and this, combined with the assumption of continual replenishing of ice nuclei removed by ice crystal formation, resulted in too many ice crystals forming by primary nucleation compared to the observations and parcel modelling

Ice formation and development in aged, wintertime cumulus over the UK: observations and modelling

In situ high resolution aircraft measurements of cloud microphysical properties were made in coordination with ground based remote sensing observations of a line of small cumulus clouds, using Radar and Lidar, as part of the Aerosol Properties, PRocesses And InfluenceS on the Earth's climate (APPRAISE) project. A narrow but extensive line (~100 km long) of shallow convective clouds over the southern UK was studied. Cloud top temperatures were observed to be higher than −8 °C, but the clouds were seen to consist of supercooled droplets and varying concentrations of ice particles. No ice particles were observed to be falling into the cloud tops from above. Current parameterisations of ice nuclei (IN) numbers predict too few particles will be active as ice nuclei to account for ice particle concentrations at the observed, near cloud top, temperatures (−7.5 °C). The role of mineral dust particles, consistent with concentrations observed near the surface, acting as high temperature IN is considered important in this case. It was found that very high concentrations of ice particles (up to 100 L−1) could be produced by secondary ice particle production providing the observed small amount of primary ice (about 0.01 L−1) was present to initiate it. This emphasises the need to understand primary ice formation in slightly supercooled clouds. It is shown using simple calculations that the Hallett-Mossop process (HM) is the likely source of the secondary ice. Model simulations of the case study were performed with the Aerosol Cloud and Precipitation Interactions Model (ACPIM). These parcel model investigations confirmed the HM process to be a very important mechanism for producing the observed high ice concentrations. A key step in generating the high concentrations was the process of collision and coalescence of rain drops, which once formed fell rapidly through the cloud, collecting ice particles which caused them to freeze and form instant large riming particles. The broadening of the droplet size-distribution by collision-coalescence was, therefore, a vital step in this process as this was required to generate the large number of ice crystals observed in the time available. Simulations were also performed with the WRF (Weather, Research and Forecasting) model. The results showed that while HM does act to increase the mass and number concentration of ice particles in these model simulations it was not found to be critical for the formation of precipitation. However, the WRF simulations produced a cloud top that was too cold and this, combined with the assumption of continual replenishing of ice nuclei removed by ice crystal formation, resulted in too many ice crystals forming by primary nucleation compared to the observations and parcel modelling

A study on wear evaluation of railway wheels based on multibody dynamics and wear computation

The wear evolution of railway wheels is a very important issue in railway engineering. In the past, the reprofiling intervals of railway vehicle steel wheels have been scheduled according to designers' experience. Today, more reliable and accurate tools in predicting wheel wear evolution and wheelset lifetime can be used in order to achieve economical and safety benefits. In this work, a computational tool that is able to predict the evolution of the wheel profiles for a given railway system, as a function of the distance run, is presented. The strategy adopted consists of using a commercial multibody software to study the railway dynamic problem and a purpose-built code for managing its pre- and post-processing data in order to compute the wear. The tool is applied here to realistic operation scenarios in order to assess the effect of some service conditions on the wheel wear progression

Whole-genome sequencing reveals host factors underlying critical COVID-19

Critical COVID-19 is caused by immune-mediated inflammatory lung injury. Host genetic variation influences the development of illness requiring critical care1 or hospitalization2,3,4 after infection with SARS-CoV-2. The GenOMICC (Genetics of Mortality in Critical Care) study enables the comparison of genomes from individuals who are critically ill with those of population controls to find underlying disease mechanisms. Here we use whole-genome sequencing in 7,491 critically ill individuals compared with 48,400 controls to discover and replicate 23 independent variants that significantly predispose to critical COVID-19. We identify 16 new independent associations, including variants within genes that are involved in interferon signalling (IL10RB and PLSCR1), leucocyte differentiation (BCL11A) and blood-type antigen secretor status (FUT2). Using transcriptome-wide association and colocalization to infer the effect of gene expression on disease severity, we find evidence that implicates multiple genes—including reduced expression of a membrane flippase (ATP11A), and increased expression of a mucin (MUC1)—in critical disease. Mendelian randomization provides evidence in support of causal roles for myeloid cell adhesion molecules (SELE, ICAM5 and CD209) and the coagulation factor F8, all of which are potentially druggable targets. Our results are broadly consistent with a multi-component model of COVID-19 pathophysiology, in which at least two distinct mechanisms can predispose to life-threatening disease: failure to control viral replication; or an enhanced tendency towards pulmonary inflammation and intravascular coagulation. We show that comparison between cases of critical illness and population controls is highly efficient for the detection of therapeutically relevant mechanisms of disease

Estimating ethnic parity in Jobcentre Plus programmes: a quantitative analysis using the Work and Pensions Longitudinal Study (WPLS)

Access to Jobcentre Plus services may be one way of overcoming any disadvantage that Ethnic Minorities may experience in the labour market and the extent to which Jobcentre Plus delivers ethnic parity in labour market outcomes from its services is of clear policy interest. This exhaustive study estimates the extent of ethnic parity in employment and benefit outcomes for 2,658 different Ethnic Minority subgroups accessing a range of Jobcentre Plus services and programmes in 2003 (including IB; IS; JSA; NDLP; ND25+; NDYP). All the analysis uses data from the Work and Pensions Longitudinal Study (WPLS), which contains longitudinal (spell-based) information on individuals’ work, benefit and pension histories. Data within the WPLS come from administrative data on benefit claims (DWP); administrative data on employment, earnings, savings, tax credits and pensions (Her Majesty’s Revenue & Customs (HMRC)); and operational data on customers’ activities (e.g. participation in back-to-work programmes) (Jobcentre Plus)

The evolution of hexapod engrailed-family genes: evidence for conservation and concerted evolution

Phylogenetic analyses imply that multiple engrailed-family gene duplications occurred during hexapod evolution, a view supported by previous reports of only a single engrailed-family gene in members of the grasshopper genus Schistocerca and in the beetle Tribolium castaneum. Here, we report the cloning of a second engrailed-family gene from Schistocerca gregaria and present evidence for two engrailed-family genes from four additional hexapod species. We also report the existence of a second engrailed-family gene in the Tribolium genome. We suggest that the engrailed and invected genes of Drosophila melanogaster have existed as a conserved gene cassette throughout holometabolous insect evolution. In total 11 phylogenetically diverse hexapod orders are now known to contain species that possess two engrailed-family paralogues, with in each case only one paralogue encoding the RS-motif, a characteristic feature of holometabolous insect invected proteins. We propose that the homeoboxes of hexapod engrailed-family paralogues are evolving in a concerted fashion, resulting in gene trees that overestimate the frequency of gene duplication. We present new phylogenetic analyses using non-homeodomain amino acid sequence that support this view. The S. gregaria engrailed-family paralogues provide strong evidence that concerted evolution might in part be explained by recurrent gene conversion. Finally, we hypothesize that the RS-motif is part of a serine-rich domain targeted for phosphorylation

Who you know, what you know and knowing the ropes: a review of evidence about access to higher education institutions in England

This paper considers the history of access to higher education in England and reviews the evidence on the progress made in widening participation and ensuring ‘fair access’ under the New Labour governments of 1997-2010 and, insofar as is possible, under the Coalition government that has been in office since 2010. While recognising that we need also to consider the nature of what students gain access to, the focus of this particular review is on evidence about inequalities in access to higher education as presently constituted, including in particular access to what are often regarded as the most ‘prestigious’ institutions. The paper considers the various ‘barriers’ to widening participation that are said to exist – from finance, aspiration and awareness and prior attainment – and assesses claims that socio-economic inequalities in access largely disappear once prior attainment is taken into account. It then discusses the role of social and cultural capitals in perpetuating inequalities both in prior attainment and access to higher education in its various forms. The importance of ‘knowing the ropes’ is highlighted and the paper ends with a discussion of the implications of the findings of the review for future approaches to policy and research in this field