772 research outputs found

    Blueshifted galaxies in the Virgo Cluster

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    We examine a sample of 65 galaxies in the Virgo cluster with negative radial velocities relative to the Local Group. Some features of this sample are pointed out. All of these objects are positioned compactly within a virial zone of radius 6{\deg} in the cluster, but their centroid is displaced relative to the dynamic center of the cluster, M87, by 1.1{\deg} to the northwest. The dwarf galaxies in this sample are clumped on a scale of ~10' (50 kpc). The observed asymmetry in the distribution of the blueshifted galaxies may be caused by infall of a group of galaxies around M86 onto the main body of the cluster. We offer another attempt to explain this phenomenon, assuming a mutual tangential velocity of ~300 km/s between the Local Group and the Virgo cluster owing to their being repelled from the local cosmological void.Comment: 10 pages, 4 figures, 1 table. Published in Astrophysics, Vol. 53, No. 1, pp. 32-41, 201

    Poroelastic Modelling of CSF circulation via the incorporation of experimentally derived microscale water transport properties

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    We outline how multicompartmental poroelasticity is applied to the study of dementia. We utilize a 3D version of our poroelastic code to investigate the effects within parenchymal tissue. This system is coupled with multiple pipelines within the VPH-DARE@IT project which account for patient/subject-specific boundary conditions in the arterial compartment, in addition to both an image segmentation-mesh and integrated cardiovascular system model pipeline respectively. This consolidated template allows for the extraction of boundary conditions to run CFD simulations for the ventricles. Finally, we outline some experimental results that will help inform the MPET system

    The ENDOCARE questionnaire (ECQ): a valid and reliable instrument to measure the patient-centeredness of endometriosis care in Europe

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    BACKGROUND: Endometriosis is prevalent and women need high-quality care, which should be patient-centered. This study aimed to develop a valid and reliable patient-centeredness questionnaire, based on a defined concept of patient-centered endometriosis care (PCEC). METHODS: A literature review, focus groups (FGs) with patients and an expert panel defined PCEC with 10 dimensions. The ENDOCARE questionnaire (ECQ) was developed. FGs resulted in 43 specific statements covering the 10 dimensions of PCEC, for which the ECQ measured 'importance' and 'performance'. Medical and demographic questions and an open question were added. The Dutch ECQ questionnaire was piloted and reciprocally translated into English and Italian. Patients with endometriosis from Belgium, The Netherlands, Italy and the UK were invited to complete the ECQ online. Item analysis, inter-item analysis and confirmatory and exploratory factor analyses (EFA) and reliability analysis were performed. The theory-driven dimensions were adapted. RESULTS: The ECQ was completed by 541 patients. Based on item analysis, five statements were deleted. Factor analysis was performed on 322 questionnaires (only from respondents with a partner). Insights from the data-driven EFA suggested adaptations of the theory-driven dimensions. The reliability statistics of 9/10 adapted theory-driven dimensions were satisfactory and the root mean square error of approximation was good. CONCLUSIONS: This study resulted in a valid and reliable instrument to measure PCEC. For data presentation, the adapted theory-driven dimensions of PCEC are preferred over the data-driven factors. The ECQ may serve to benchmark patient-centeredness, conduct cross-cultural European research and set targets for improvement

    Walk with Me: a protocol for a pilot RCT of a peer-led walking programme to increase physical activity in inactive older adults

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    Background: Levels of physical activity decline with age. Some of the most disadvantaged individuals in society, such as those from lower socio-economic position, are also the most inactive. Increasing physical activity levels, particularly among those most inactive, is a public health priority. Peer-led physical activity interventions may offer a model to increase physical activity in the older adult population. This study aims to test the feasibility of a peer-led, multicomponent physical activity intervention in socio-economically disadvantaged community dwelling older adults. Methods: The Medical Research Council framework for developing and evaluating complex interventions will be used to design and test the feasibility of a randomised controlled trial (RCT) of a multicomponent peer-led physical activity intervention. Data will be collected at baseline, immediately after the intervention (12 weeks) and 6 months after baseline measures. The pilot RCT will provide information on recruitment of peer mentors and participants and attrition rates, intervention fidelity, and data on the variability of the primary outcome (minutes of moderate to vigorous physical activity measured with an accelerometer). The pilot trail will also assess the acceptability of the intervention and identify potential resources needed to undertake a definitive study. Data analyses will be descriptive and include an evaluation of eligibility, recruitment, and retention rates. The findings will be used to estimate the sample size required for a definitive trial. A detailed process evaluation using qualitative and quantitative methods will be conducted with a variety of stakeholders to identify areas of success and necessary improvements. Discussion: This paper describes the protocol for the ‘Walk with Me’ pilot RCT which will provide the information necessary to inform the design and delivery of a fully powered trial should the Walk with Me intervention prove feasible

    Astrocytic Ion Dynamics: Implications for Potassium Buffering and Liquid Flow

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    We review modeling of astrocyte ion dynamics with a specific focus on the implications of so-called spatial potassium buffering, where excess potassium in the extracellular space (ECS) is transported away to prevent pathological neural spiking. The recently introduced Kirchoff-Nernst-Planck (KNP) scheme for modeling ion dynamics in astrocytes (and brain tissue in general) is outlined and used to study such spatial buffering. We next describe how the ion dynamics of astrocytes may regulate microscopic liquid flow by osmotic effects and how such microscopic flow can be linked to whole-brain macroscopic flow. We thus include the key elements in a putative multiscale theory with astrocytes linking neural activity on a microscopic scale to macroscopic fluid flow.Comment: 27 pages, 7 figure

    Peer-led walking programme to increase physical activity in inactive 60- to 70-year-olds: Walk with Me pilot RCT

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    Background Levels of physical activity decline with age. Some of the most disadvantaged individuals in society, such as those with a lower rather than a higher socioeconomic position, are also the most inactive. Peer-led physical activity interventions may offer a model to increase physical activity in these older adults and thus help reduce associated health inequalities. This study aims to develop and test the feasibility of a peer-led, multicomponent physical activity intervention in socioeconomically disadvantaged community-dwelling older adults. Objectives The study aimed to develop a peer-led intervention through a rapid review of previous peer-led interventions and interviews with members of the target population. A proposed protocol to evaluate its effectiveness was tested in a pilot randomised controlled trial (RCT). Design A rapid review of the literature and the pilot study informed the intervention design; a pilot RCT included a process evaluation of intervention delivery. Setting Socioeconomically disadvantaged communities in the South Eastern Health and Social Care Trust and the Northern Health and Social Care Trust in Northern Ireland. Participants Fifty adults aged 60–70 years, with low levels of physical activity, living in socioeconomically disadvantaged communities, recruited though community organisations and general practices. Interventions ‘Walk with Me’ is a 12-week peer-led walking intervention based on social cognitive theory. Participants met weekly with peer mentors. During the initial period (weeks 1–4), each intervention group participant wore a pedometer and set weekly step goals with their mentor’s support. During weeks 5–8 participants and mentors met regularly to walk and discuss step goals and barriers to increasing physical activity. In the final phase (weeks 9–12), participants and mentors continued to set step goals and planned activities to maintain their activity levels beyond the intervention period. The control group received only an information booklet on active ageing. Main outcome measures Rates of recruitment, retention of participants and completeness of the primary outcome [moderate- and vigorous-intensity physical activity measured using an ActiGraph GT3X+ accelerometer (ActiGraph, LLC, Pensacola, FL, USA) at baseline, 12 weeks (post intervention) and 6 months]; acceptability assessed through interviews with participants and mentors. Results The study planned to recruit 60 participants. In fact, 50 eligible individuals participated, of whom 66% (33/50) were female and 80% (40/50) were recruited from general practices. At 6 months, 86% (43/50) attended for review, 93% (40/43) of whom returned valid accelerometer data. Intervention fidelity was assessed by using weekly step diaries, which were completed by both mentors and participants for all 12 weeks, and checklists for the level of delivery of intervention components, which was high for the first 3 weeks (range 49–83%). However, the rate of return of checklists by both mentors and participants diminished thereafter. Outcome data indicate that a sample size of 214 is required for a definitive trial. Limitations The sample was predominantly female and somewhat active. Conclusions The ‘Walk with Me’ intervention is acceptable to a socioeconomically disadvantaged community of older adults and a definitive RCT to evaluate its effectiveness is feasible. Some modifications are required to ensure fidelity of intervention delivery is optimised. Future research needs to identify methods to recruit males and less active older adults into physical activity interventions

    A high-throughput behavioral paradigm for Drosophila olfaction - The Flywalk

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    How can odor-guided behavior of numerous individual Drosophila be assessed automatically with high temporal resolution? For this purpose we introduce the automatic integrated tracking and odor-delivery system Flywalk. In fifteen aligned small wind tunnels individual flies are exposed to repeated odor pulses, well defined in concentration and timing. The flies' positions are visually tracked, which allows quantification of the odor-evoked walking behavior with high temporal resolution of up to 100 ms. As a demonstration of Flywalk we show that the flies' behavior is odorant-specific; attractive odors elicit directed upwind movements, while repellent odors evoke decreased activity, followed by downwind movements. These changes in behavior differ between sexes. Furthermore our findings show that flies can evaluate the sex of a conspecific and males can determine a female's mating status based on olfactory cues. Consequently, Flywalk allows automatic screening of individual flies for their olfactory preference and sensitivity

    A review of elliptical and disc galaxy structure, and modern scaling laws

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    A century ago, in 1911 and 1913, Plummer and then Reynolds introduced their models to describe the radial distribution of stars in `nebulae'. This article reviews the progress since then, providing both an historical perspective and a contemporary review of the stellar structure of bulges, discs and elliptical galaxies. The quantification of galaxy nuclei, such as central mass deficits and excess nuclear light, plus the structure of dark matter halos and cD galaxy envelopes, are discussed. Issues pertaining to spiral galaxies including dust, bulge-to-disc ratios, bulgeless galaxies, bars and the identification of pseudobulges are also reviewed. An array of modern scaling relations involving sizes, luminosities, surface brightnesses and stellar concentrations are presented, many of which are shown to be curved. These 'redshift zero' relations not only quantify the behavior and nature of galaxies in the Universe today, but are the modern benchmark for evolutionary studies of galaxies, whether based on observations, N-body-simulations or semi-analytical modelling. For example, it is shown that some of the recently discovered compact elliptical galaxies at 1.5 < z < 2.5 may be the bulges of modern disc galaxies.Comment: Condensed version (due to Contract) of an invited review article to appear in "Planets, Stars and Stellar Systems"(www.springer.com/astronomy/book/978-90-481-8818-5). 500+ references incl. many somewhat forgotten, pioneer papers. Original submission to Springer: 07-June-201

    Retention of Memory through Metamorphosis: Can a Moth Remember What It Learned As a Caterpillar?

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    Insects that undergo complete metamorphosis experience enormous changes in both morphology and lifestyle. The current study examines whether larval experience can persist through pupation into adulthood in Lepidoptera, and assesses two possible mechanisms that could underlie such behavior: exposure of emerging adults to chemicals from the larval environment, or associative learning transferred to adulthood via maintenance of intact synaptic connections. Fifth instar Manduca sexta caterpillars received an electrical shock associatively paired with a specific odor in order to create a conditioned odor aversion, and were assayed for learning in a Y choice apparatus as larvae and again as adult moths. We show that larvae learned to avoid the training odor, and that this aversion was still present in the adults. The adult aversion did not result from carryover of chemicals from the larval environment, as neither applying odorants to naïve pupae nor washing the pupae of trained caterpillars resulted in a change in behavior. In addition, we report that larvae trained at third instar still showed odor aversion after two molts, as fifth instars, but did not avoid the odor as adults, consistent with the idea that post-metamorphic recall involves regions of the brain that are not produced until later in larval development. The present study, the first to demonstrate conclusively that associative memory survives metamorphosis in Lepidoptera, provokes intriguing new questions about the organization and persistence of the central nervous system during metamorphosis. Our results have both ecological and evolutionary implications, as retention of memory through metamorphosis could influence host choice by polyphagous insects, shape habitat selection, and lead to eventual sympatric speciation

    A single, one-off measure of depression and anxiety predicts future symptoms, higher healthcare costs, and lower quality of life in coronary heart disease patients: Analysis from a multi-wave, primary care cohort study

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    To determine whether a one-off, baseline measure of depression and anxiety in a primary care, coronary heart disease (CHD) population predicts ongoing symptoms, costs, and quality of life across a 3-year follow-up.Longitudinal cohort study.16 General Practice surgeries across South-East London.803 adults (70% male, mean age 71 years) contributing up to 7 follow-up points.Ongoing reporting of symptoms, health care costs, and quality of life.At baseline, 27% of the sample screened positive for symptoms of depression and anxiety, as measured by the Hospital Anxiety and Depression Scale (HADS). The probability of scoring above the cut-off throughout the follow-up was 71.5% (p<0.001) for those screening positive at baseline, and for those screening negative, the probability of scoring below the cut-off throughout the follow-up was 97.6% (p<0.001). Total health care costs were 39% higher during follow-up for those screening positive (p<0.05). Quality of life as measured by the SF-12 was lower on the mental component during follow-up for those screening positive (-0.75, CI -1.53 to 0.03, p = 0.059), and significantly lower on the physical component (-4.99, CI -6.23 to -.376, p<0.001).A one-off measure for depression and anxiety symptoms in CHD predicts future symptoms, costs, and quality of life over the subsequent three-years. These findings suggest symptoms of depression and anxiety in CHD persist throughout long periods and are detrimental to a patient's quality of life, whilst incurring higher health care costs for primary and secondary care services. Screening for these symptoms at the primary care level is important to identify and manage patients at risk of the negative effects of this comorbidity. Implementation of screening, and possible collaborative care strategies and interventions that help mitigate this risk should be the ongoing focus of researchers and policy-makers
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