11,686 research outputs found

    Sensitivity and foreground modelling for large-scale CMB B-mode polarization satellite missions

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    The measurement of the large-scale B-mode polarization in the cosmic microwave background (CMB) is a fundamental goal of future CMB experiments. However, because of unprecedented sensitivity, future CMB experiments will be much more sensitive to any imperfect modelling of the Galactic foreground polarization in the reconstruction of the primordial B-mode signal. We compare the sensitivity to B-modes of different concepts of CMB satellite missions (LiteBIRD, COrE, COrE+, PRISM, EPIC, PIXIE) in the presence of Galactic foregrounds. In particular, we quantify the impact on the tensor-to-scalar parameter of incorrect foreground modelling in the component separation process. Using Bayesian fitting and Gibbs sampling, we perform the separation of the CMB and Galactic foreground B-modes. The recovered CMB B-mode power spectrum is used to compute the likelihood distribution of the tensor-to-scalar ratio. We focus the analysis to the very large angular scales that can be probed only by CMB space missions, i.e. the Reionization bump, where primordial B-modes dominate over spurious B-modes induced by gravitational lensing. We find that fitting a single modified blackbody component for thermal dust where the "real" sky consists of two dust components strongly bias the estimation of the tensor-to-scalar ratio by more than 5{\sigma} for the most sensitive experiments. Neglecting in the parametric model the curvature of the synchrotron spectral index may bias the estimated tensor-to-scalar ratio by more than 1{\sigma}. For sensitive CMB experiments, omitting in the foreground modelling a 1% polarized spinning dust component may induce a non-negligible bias in the estimated tensor-to-scalar ratio.Comment: 20 pages, 8 figures, 6 tables. Updated to match version accepted by MNRA

    Representation of transport: A Rural Destination Analysis

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    Moscovici’s social representations perspective is applied to a study of transport in a rural destination. The principles are demonstrated using empirical data from a questionnaire survey, developed following in-depth qualitative research. The data analysis strategy was founded on inductive reasoning, by employing cluster analysis and correspondence analysis. A social representations analysis demonstrates how individuals draw on socially accepted explanations of transport where they have little or no direct knowledge or experience of the actual transport modes (notably the alternatives to the car). By so doing, ideas are further perpetuated. Importantly there is ambiguity surrounding responsibility to take positive action yet a key to addressing transport issues is acknowledgement of responsibility. Keywords: social representations, transport, rural destinations

    Breast feeding practices and views among diabetic women: a retrospective cohort study

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    Objective: to explore the pattern and experiences of breast-feeding practices among diabetic women. Design: retrospective cohort study using maternal records and postal questionnaires in a Baby-Friendly hospital. Participants: diabetic mothers including women with gestational diabetes, and type 1 and 2 diabetes mellitus. Findings: from the total group of respondents, 81.9% intended to breast feed. The actual breast feeding rates were 81.9% at birth, 68.1% at 2 weeks and 28.7% at 6 months postpartum. Major themes that were identified from women's experiences included information and advice, support vs. pressure, classification and labelling, and expectations. Conclusions: more than two-thirds of the diabetic women intended to breast feed and actually did breast feed in this study. For both the total study population and the type 1 and 2 diabetics alone, more than half were still breast feeding at 2 weeks postpartum, and approximately one-third were still breast feeding at 6 months postpartum. Implications for practice: structured support, provided for women through Baby-Friendly initiatives, was appreciated by the diabetic women in this study. The extent to which this support influenced the highly successful breast feeding practices in this group of women needs focused investigation. The need for a delicate balancing act between pressure and advice in order to prevent coercion was noted.</p

    Human behavioural analysis with self-organizing map for ambient assisted living

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    This paper presents a system for automatically classifying the resting location of a moving object in an indoor environment. The system uses an unsupervised neural network (Self Organising Feature Map) fully implemented on a low-cost, low-power automated home-based surveillance system, capable of monitoring activity level of elders living alone independently. The proposed system runs on an embedded platform with a specialised ceiling-mounted video sensor for intelligent activity monitoring. The system has the ability to learn resting locations, to measure overall activity levels and to detect specific events such as potential falls. First order motion information, including first order moving average smoothing, is generated from the 2D image coordinates (trajectories). A novel edge-based object detection algorithm capable of running at a reasonable speed on the embedded platform has been developed. The classification is dynamic and achieved in real-time. The dynamic classifier is achieved using a SOFM and a probabilistic model. Experimental results show less than 20% classification error, showing the robustness of our approach over others in literature with minimal power consumption. The head location of the subject is also estimated by a novel approach capable of running on any resource limited platform with power constraints

    A computer vision approach to classification of birds in flight from video sequences

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    Bird populations are an important bio-indicator; so collecting reliable data is useful for ecologists helping conserve and manage fragile ecosystems. However, existing manual monitoring methods are labour-intensive, time-consuming, and error-prone. The aim of our work is to develop a reliable system, capable of automatically classifying individual bird species in flight from videos. This is challenging, but appropriate for use in the field, since there is often a requirement to identify in flight, rather than when stationary. We present our work in progress, which uses combined appearance and motion features to classify and present experimental results across seven species using Normal Bayes classifier with majority voting and achieving a classification rate of 86%

    Ingestive behaviour and physiology of the medicinal leech

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    Ingestion lasts 25 min in Hirudo medicinalis and is characterized by pharyngeal peristalsis which fills the crop. This peristalsis has an initial rate of 2.4 Hz which decays smoothly to 1.2 Hz at termination of ingestion. During ingestion, the leech body wall undergoes peristalsis which appears to aid in filling the crop diverticula. Body peristalsis begins at a rate of 10 min^(-1) and decreases linearly to 2 min^(-1) at termination. The body also undergoes dorsoventral flexions when blood flow is occluded. Blood meal size increases slightly with leech size: 8.4 g for 1-g leeches and 9.7 g for 2-g leeches. However, relative meal size decreases markedly with increasing animal size; from 8.15 times body mass for 1-g to 4.80 times for 2-g leeches. When intact leeches were exposed to micromolar concentrations of serotonin, there was an increase in the rate of pharyngeal peristalsis and the size of the blood meals. Leeches excrete the plasma from their ingested blood meals. Excretion is activated during ingestion, which increases feeding efficiency by increasing the proportion of blood cells in the ingestate. Excretion continues for 4–6 days following ingestion, removing all the remaining plasma from the ingestate. Leech ingestion comprises stereotyped muscular movements, secretion of saliva and excretion of plasma. A strikingly similar feeding physiology is seen in the blood-sucking insect Rhodnius, and we suggest that efficient sanguivory may require the convergent evolution of similar ingestive mechanisms

    Alien Registration- Dickinson, John K. (Houlton, Aroostook County)

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    https://digitalmaine.com/alien_docs/36137/thumbnail.jp

    Galaxy Clustering at z~3

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    Galaxies at very high redshift (z~3 or greater) are now accessible to wholesale observation, making possible for the first time a robust statistical assessment of their spatial distribution at lookback times approaching ~90% of the age of the Universe. This paper summarizes recent progress in understanding the nature of these early galaxies, concentrating in particular on the clustering properties of photometrically selected ``Lyman break'' galaxies. Direct comparison of the data to predictions and physical insights provided by galaxy and structure formation models is particularly straightforward at these early epochs, and results in critical tests of the ``biased'', hierarchical galaxy formation paradigm.Comment: Presented at Royal Society Discussion Meeting, March 1998, "Large Scale Structure in the Universe", 14 pages LaTeX, 7 ps figures, uses rspublic.sty (included

    Fall prevention in the community: what older people say they need

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    Original article can be found at: http://www.bjcn.co.uk/ Copyright MA HealthcareUptake of and adherence to fall prevention interventions is often poor and we know little about how older people’s perceptions of and beliefs about fall prevention interventions affect uptake. This study aimed to explore older people’s perceptions of the facilitators and barriers to participation in fall prevention interventions. We undertook a qualitative study with older people who had taken part in, declined to participate or adhere to fall prevention interventions using semi-structured interviews (n=65), and 17 focus groups (n=122) with older people (including 32 South Asian and 30 Chinese older people) in primary and community care settings in the South of England. A number of factors acted as either barriers or facilitators to uptake of interventions. Older people also made recommendations for improving access to interventions. Community nurses are ideally placed to screen older people, identify those at risk of falling and refer them to appropriate interventions as well as providing health promotion and education.Peer reviewe
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