483 research outputs found

    Galactic Outflows and the pollution of the Galactic Environment by Supernovae

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    We here explore the effects of the SN explosions into the environment of star-forming galaxies like the Milky Way. Successive randomly distributed and clustered SNe explosions cause the formation of hot superbubbles that drive either fountains or galactic winds above the galactic disk, depending on the amount and concentration of energy that is injected by the SNe. In a galactic fountain, the ejected gas is re-captured by the gravitational potential and falls back onto the disk. From 3D nonequilibrium radiative cooling hydrodynamical simulations of these fountains, we find that they may reach altitudes up to about 5 kpc in the halo and thus allow for the formation of the so called intermediate-velocity-clouds (IVCs) which are often observed in the halos of disk galaxies. The high-velocity-clouds that are also observed but at higher altitudes (of up to 12 kpc) require another mechanism to explain their production. We argue that they could be formed either by the capture of gas from the intergalactic medium and/or by the action of magnetic fields that are carried to the halo with the gas in the fountains. Due to angular momentum losses to the halo, we find that the fountain material falls back to smaller radii and is not largely spread over the galactic disk. Instead, the SNe ejecta fall nearby the region where the fountain was produced, a result which is consistent with recent chemical models of the galaxy. The fall back material leads to the formation of new generations of molecular clouds and to supersonic turbulence feedback in the disk.Comment: 10 pages, 5 figures; paper of invited talk for the Procs. of the 2007 WISER Workshop (World Space Environment Forum), Alexandria, Egypt, October 2007, Spa. Sci. Rev

    Community health careworkers in Guinea-Bissau: who is performing better?

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    In the Community Health Workers settings in Guinea-Bissau, we explore several determinants of performance. Firstly, we investigate the effect of socio-demographic characteristics like education, gender, wealth, job status and community "embededdness". We provide evidence for significant differences due to education, gender or job status and community interaction. We also research on the relation between motivation and performance, concluding extrinsically motivated agents performbetter, as opposed to agents with stronger antisocial impact perceptions, who performworse. Given the richness of our data, we also explore differences in ethnicity in terms of performance outcomes or motivation orientations, but in both cases we find few significant results

    Describing Self-Care in Italian Adults with Heart Failure and Identifying Determinants of Poor Self-Care

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    Background: Self-care improves outcomes in patients with heart failure; however, no studies have been conducted on this topic in Italy. Aims: We aimed to describe self-care in Italian adults with heart failure and to identify sociodemographic and clinical determinants of self-care. Methods: A cross-sectional design was used to study 1192 heart failure patients enrolled across Italy. We measured self-care using the Self-Care of Heart Failure Index version 6.2, which measures self-care maintenance, management and confidence. Sociodemographic and clinical data were tested as potential determinants of self-care. Results: The mean age of the sample was 72 (SD = 11) years; 58% were male. In the three areas of self-care, scores ranged from 53.18 to 55.26 and few people were adequate in self-care (14.5% to 24.4% of the sample). Self-care behaviours particularly low in this population were symptom monitoring, exercise, use of reminders to take medicines and symptom recognition. Confidence in the ability to keep oneself free of symptoms and relieve symptoms was low. Taking fewer medications, poor cognition, older age, having a caregiver, being male and having heart failure for a shorter time predicted poor self-care maintenance. Poor cognition, not being employed, being male, and having worse New York Heart Association class predicted poor self-care management. Poor cognition, taking fewer mediations, older age, and male gender predicted poor self-care confidence. Conclusion: Self-care is poor in Italian heart failure patients. Determinants of poor self-care identified in this study can help to target patients’ education. Male gender and poor cognition were consistently associated with poor self-care maintenance, management and confidence

    Hemodynamic responses during and after multiple sets of stretching exercises performed with and without the Valsalva maneuver

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    OBJECTIVE: This study investigated the acute hemodynamic responses to multiple sets of passive stretching exercises performed with and without the Valsalva maneuver. METHODS: Fifteen healthy men aged 21 to 29 years with poor flexibility performed stretching protocols comprising 10 sets of maximal passive unilateral hip flexion, sustained for 30 seconds with equal intervals between sets. Protocols without and with the Valsalva maneuver were applied in a random counterbalanced order, separated by 48-hour intervals. Hemodynamic responses were measured by photoplethysmography pre-exercise, during the stretching sets, and post-exercise. RESULTS: The effects of stretching sets on systolic and diastolic blood pressure were cumulative until the fourth set in protocols performed with and without the Valsalva maneuver. The heart rate and rate pressure product increased in both protocols, but no additive effect was observed due to the number of sets. Hemodynamic responses were always higher when stretching was performed with the Valsalva maneuver, causing an additional elevation in the rate pressure product. CONCLUSIONS: Multiple sets of unilateral hip flexion stretching significantly increased blood pressure, heart rate, and rate pressure product values. A cumulative effect of the number of sets occurred only for systolic and diastolic blood pressure, at least in the initial sets of the stretching protocols. The performance of the Valsalva maneuver intensified all hemodynamic responses, which resulted in significant increases in cardiac work during stretching exercises

    Multi-views Embedding for Cattle Re-identification

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    People re-identification task has seen enormous improvements in the latest years, mainly due to the development of better image features extraction from deep Convolutional Neural Networks (CNN) and the availability of large datasets. However, little research has been conducted on animal identification and re-identification, even if this knowledge may be useful in a rich variety of different scenarios. Here, we tackle cattle re-identification exploiting deep CNN and show how this task is poorly related to the human one, presenting unique challenges that make it far from being solved. We present various baselines, both based on deep architectures or on standard machine learning algorithms, and compared them with our solution. Finally, a rich ablation study has been conducted to further investigate the unique peculiarities of this task

    Psychometric Testing of the Self-Care of Heart Failure Index Version 6.2

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    The Self‐Care of Heart Failure Index Version 6.2 (SCHFI v.6.2) is widely used, but its psychometric profile is still questioned. In a sample of 659 heart failure patients from Italy, we performed confirmatory factor analysis (CFA) to test the original construct of the SCHFI v.6.2 scales (Self‐Care Maintenance, Self‐Care Management, and Self‐Care Confidence), with limited success. We then used exploratory factor analysis to determine the presence of separate scale dimensions, followed by CFA in a separate sub‐sample. Construct validity of individual scales showed excellent fit indices: CFI = .92, RMSEA = .05 for the Self‐Care Maintenance Scale; CFI = .95, RMSEA = .07 for the Self‐Care Management Scale; CFI = .99, RMSEA = .02 for the Self‐Care Confidence scale. Contrasting groups validity, internal consistency, and test‐retest reliability were supported as well. This evidence provides a new understanding of the structure of the SCHFI v.6.2 and supports its use in clinical practice and research
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