Melt droplet formation in energetic impacts

Impacts between rocky bodies at velocities exceeding about 15 km/sec are capable of melting or vaporizing both the impacting object and a portion of the target. Geological materials initially shocked to high pressure approach the liquid-vapor phase boundary from the liquid side as they decompress, breaking up into an expanding spray of liquid droplets. A simple theory is presented for estimating the sizes of these droplets as a function of impactor size and velocity. It is shown that these sizes are consistent with observations of microtektites and spherules found in the Cretaceous-Tertiary boundary layer, the Acraman impact structure, Archean beds in South Africa and lunar regolith. The model may also apply to the formation of chondrules

Production of impact melt in craters on Venus, Earth, and the moon

Impact craters imaged by Magellan clearly show large amounts of flow-like ejecta whose morphology suggests that the flows comprise low-viscosity material. It was suggested that this material may be either turbidity flows or very fine-grained ejecta, flows of ejecta plus magma, or impact melts. The last of these hypotheses is considered. If these flows are composed of impact melts, there is much more melt relative to the crater volume than is observed on the moon. The ANEOS equation of state program was used for dunite to estimate the shock pressures required for melting, with initial conditions appropriate for Venus, Earth, and the moon. A simple model was then developed, based on the Z-model for excavation flow and on crater scaling relations that allow to estimate the ratio of melt ejecta to total ejecta as a function of crater size on the three bodies

MBS Ratings and the Mortgage Credit Boom

We study credit ratings on subprime and Alt-A mortgage-backed securities (MBS) deals issued between 2001 and 2007, the period leading up to the subprime crisis. The fraction of highly-rated securities in each deal is decreasing in mortgage credit risk (measured either ex-ante or ex-post), suggesting ratings contain useful information for investors. However, we also find evidence of significant time-variation in risk-adjusted credit ratings, including a progressive decline in standards around the MBS market peak between the start of 2005 and mid-2007. Conditional on initial ratings, we observe underperformance (high mortgage defaults and losses, and large rating downgrades) amongst deals with observably higher-risk mortgages based on a simple ex-ante model, and deals with a high fraction of opaque low-documentation loans. These findings hold over the entire sample period, not just for deal cohorts most affected by the crisis.

“There isn't anybody else like me around here”: the insider-outsider status of LGBT residents in housing with care schemes for older people

The intersections between aging, social minority status and housing needs in later life is a neglected area of sociological exploration, even more so for older people who identify as lesbian, gay, bisexual and trans (LGBT). Recent sociological findings indicate that older LGBT people in housing schemes stress the importance of bonding social capital and look to other people in their social networks who reflect their identities and experiences as sources of support. In this paper, we examine the insider-outsider status occupied by older LGBT residents living in housing schemes that provide some form of care and support, for example extra care and independent living schemes. We present qualitative findings generated from a mixed-methods study of social inclusion practices in housing with care in England and Wales (UK) (2019-22). In this study 15 LGBT residents participated in semi-structured interviews (55–79 years of age) across a total of 31 interviews. Through a queer gerontological lens we examine how older LGBT people are socially situated within mainstream housing schemes in which they experience partial visibility while also encountering exclusionary pressures that locate them as “the other.” This insider-outsider status undermines the premise of housing with care schemes to provide safe, secure spaces to grow old. We discuss three core themes: (1) how LGBT residents navigate their outsider status in scheme life and how the intersection of disability and minority status amplifies this social location; (2) the exclusionary practices exercised by other residents that reinforce boundaries of sexual and gender normalcy; and, (3) the heightened importance of maintaining external social connections among LGBT residents. We conclude by introducing an alternative notion of marginal aging and expanding on the implications for housing providers, reflecting on their responsibilities for promoting and maintaining queer-friendly environments

Standing Practice In Rehabilitation Early after Stroke (SPIRES): a functional standing frame programme (prolonged standing and repeated sit to stand) to improve function and quality of life and reduce neuromuscular impairment in people with severe sub-acute stroke-a protocol for a feasibility randomised controlled trial.

Background: The most common physical deficit caused by a stroke is muscle weakness which limits a person's mobility. Mobility encompasses activities necessary for daily functioning: getting in and out bed, on/off toilet, sitting, standing and walking. These activities are significantly affected in people with severe stroke who typically spend most of their time in bed or a chair and are immobile. Immobility is primarily caused by neurological damage but exacerbated by secondary changes in musculoskeletal and cardiorespiratory systems. These secondary changes can theoretically be prevented or minimised by early mobilisation, in this case standing up early post-stroke.Standing up early post-stroke has been identified as an important priority for people who have suffered a severe stroke. However, trials of prolonged passive standing have not demonstrated any functional improvements. Conversely, task-specific training such as repeated sit-to-stand has demonstrated positive functional benefits. This feasibility trial combines prolonged standing and task-specific strength training with the aim of determining whether this novel combination of physiotherapy interventions is feasible for people with severe stroke as well as the overall feasibility of delivering the trial. Methods/design: This is a pragmatic multi-centre parallel single-blinded two-armed feasibility randomised controlled trial. Fifty people with a diagnosis of severe stroke will be randomly allocated to either the functional standing frame programme or usual physiotherapy. All patient participants will be assessed at baseline and followed up at 3 weeks, then 3, 6 and 12 months post-randomisation. Trial objectives are to determine the feasibility according to the following indicators:: (i) Process: recruitment and retention rate, ability to consent, eligibility criteria, willingness/ability of physiotherapists to recruit, willingness of patients to be randomised, and acceptability of the intervention; (ii) Resource: burden and potential costs; (iii) Management: treatment fidelity, participant adherence, acceptability and completeness of outcome measures, impact and management or orthostatic hypotension; and (iv) Safety: number and nature of adverse and serious adverse events. Discussion: The functional standing frame programme addresses a key concern for people who have suffered a severe stroke. However, several uncertainties exist which need to be understood prior to progressing to a full-scale trial, including acceptability and tolerance of the functional standing frame programme intervention and practicality of the trial procedures. This feasibility trial will provide important insights to resolve these uncertainties. Trial registration: International Standard Randomised Controlled Trial Number ISRCTN15412695. Registration on 19 December 2016

Object-based warping in three-dimensional environments

Object-based warping is a powerful visual illusion wherein space between features within figural regions is regularly overestimated compared with those within ground regions. Originally, the effect was only examined in displays of two-dimensional (2D) stimuli. The present study sought to examine whether object-based warping persists in more naturalistic viewing conditions, where additional contextual cues are present. Stimuli were presented with either three-dimensional (3D) printed objects (Experiment 1) or 3D objects in virtual reality (Experiments 2–4). The testing metric was actual distance of features (dots) compared with estimated distances made by participants. Responses for the 3D printed stimuli were measured with replica dots on a slide ruler device. The virtual reality experiments collected responses either with a computer mouse or motion-tracked controller and included manipulations of object type, spatial separation, viewing distance of stimuli, and head motion. A standard warping effect in 3D was observed in all experiments, although the effect was not present in one condition that elicits warping in 2D (Occluded Rectangle). The final experiment resolves this discrepancy by reducing the multicomponent object (Occluded Rectangle) to a single component figure, while demonstrating the influence of depth cues on the warping effect under occlusion. Collectively, these experiments reveal that object-based warping is a powerful effect, even in naturalistic settings

The impact of COVID-19 lockdown measures on older residents' social connections and everyday wellbeing within housing schemes that provide care and support in England and Wales

The COVID-19 pandemic and the lockdown measures imposed as a result affected the lives of people in all parts of society across the world. In 2020, during the first UK national lockdown, older adults (aged 70 years and over) were told to ‘shield’ within their homes, as they were regarded as being at higher risk of serious COVID-19 infection compared to other age groups. This paper explores older adults' experiences of COVID-19 lockdown measures whilst living in housing with care schemes for older people. The purpose is to examine the impact of the lockdown measures on scheme life including social connections amongst residents and their general everyday wellbeing during this time. We present qualitative findings based on interviews with 72 residents who took part in longitudinal and cross-sectional interviews across 26 housing with care schemes. Data were analysed using a thematic framework approach to examine specifically their experiences of living in housing with care schemes during the 2020 UK lockdown. The paper highlights that COVID-19 restrictions had a detrimental impact on the social connections and interactions of older residents living in housing with care schemes, as well as on their feelings of autonomy and independence. Despite this, residents adapted and coped with self-isolation restrictions and sought out positive ways to maintain social contact with others inside and outside to the scheme. We further highlight the tensions that providers of housing for older adults faced in promoting residents' autonomy and connectedness whilst also trying to provide a safe living environment and protect residents from risk of COVID-19 infection. Our findings apply not only to a pandemic situation but to the broader understanding of how housing with care for older adults must navigate between autonomy and support

Insights into membrane protein–lipid interactions from free energy calculations

Integral membrane proteins are regulated by specific interactions with lipids from the surrounding bilayer. The structures of protein–lipid complexes can be determined through a combination of experimental and computational approaches, but the energetic basis of these interactions is difficult to resolve. Molecular dynamics simulations provide the primary computational technique to estimate the free energies of these interactions. We demonstrate that the energetics of protein–lipid interactions may be reliably and reproducibly calculated using three simulation-based approaches: potential of mean force calculations, alchemical free energy perturbation, and well-tempered metadynamics. We employ these techniques within the framework of a coarse-grained force field and apply them to both bacterial and mammalian membrane protein–lipid systems. We demonstrate good agreement between the different techniques, providing a robust framework for their automated implementation within a pipeline for annotation of newly determined membrane protein structures