6,185 research outputs found

    Development and demonstration of flueric sounding rocket motor ignition

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    An analytical and experimental program is described which established a flueric rocket motor ignition system concept incorporating a pneumatic match with a simple hand pump as the only energy source. An evaluation was made of this concept to determine the margins of the operating range and capabilities of every component of the system. This evaluation included a determination of power supply requirements, ignitor geometry and alinement, ignitor/propellant interfacing and materials and the effects of ambient temperatures and pressure. It was demonstrated that an operator using a simple hand pump for 30 seconds could ignite BKNO3 at a standoff distance of 100 m (330 ft) with the only connection to the ignitor being a piece of plastic pneumatic tubing

    Ignition of sounding rocket motors with hand-pumped air

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    Method demonstrates inexpensive, safe, and foolproof concept for solid propellant rocket motors, using simple handpump to deliver air. Flueric ignition was accomplished using system without stored energy and with complete absence of electrical energy and wiring

    Meshless Numerical Solution of Boundary Integral Equations based on Non Uniform Rational Basis-Splines

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    Determinants associated with obesity and physical activity in the public and private schools of the city of palermo

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    Introduction: Obesity is a medical condition associated with premature death and it is a risk factor for many chronic diseases. In this context, performing a regular physical activity promotes a healthy lifestyle, with significant health benefits. The aim of the study was to investigate behaviors that increase the risk of obesity and the determinants that encourage physical activity among adolescents. Materials and methods: The HBSC (Health Behavior in School-aged Children) questionnaire was administered to students in Palermo's private and public schools. For the sampling of public schools the protocol of the HBSC Surveillance System was followed; for the private ones it was opportunistic. Results: Private school students are more likely to exercise more than 3 days per week (OR 1.58) and are more likely to exercise more than 2 times a week (OR 2.08). Obese students in private schools in Palermo are more likely to perform physical activity for less than 3 days a week (OR 3.52) and a higher risk of not having breakfast (OR 10.11) and a snack between main meals (OR 3.82) every day. For all the schools examined, it emerged that obese subjects are more likely not to consume fruit (OR 3.13), to stay more than 6 hours a day in front of PCs and video games (OR 3.24) and more than 2 hours a day in front of TV (OR 3.79). Male students are more likely to perform physical activity for more than 3 days per week (OR 1.48) and intense physical activity at least 2 times per week (OR 1.76) Conclusions: It is necessary to intervene early with training on school and family in order to promote correct and responsible food choices and increase the level of physical activity among students. Therefore prevention interventions must be an integral part of coherent strategies based on tests of agreed effectiveness in order to minimize the risk linked to the development of diseases

    The variable ionized absorber in the Seyfert 2 Mrk 348

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    We present the results of the analysis of the X-ray spectrum of the Seyfert 2 Mrk 348, observed by Suzaku and XMM-Newton. The overall spectrum of Mrk 348 can be described by a primary power law continuum seen through three layers of absorption, of which one is neutral and two are ionised. Comparing Suzaku (2008) and XMM-Newton (2002) observations we find variability of the X-ray spectral curvature. We suggest that the variability can be explained through the change of column density of both the neutral and one of the ionised absorbers, together with a variation of the ionisation level of the same absorber. We thus confirm one of the main features presented in past works, where intrinsic column density variability up to 1023\sim 10^{23}~cm2^{-2} was observed on time scales of months. We also find that the photon index of the underlying power law continuum (Γ1.8\Gamma \sim 1.8) is in agreement with the previous observations of this Seyfert 2.Comment: 13 pages, 6 figure

    TRACHEOSTOMY MECHANICAL VENTILATION IN PATIENTS WITH AMYOTROPHIC LATERAL SCLEROSIS: CLINICAL FEATURES AND SURVIVAL ANALYSIS.

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    Background: Tracheostomy mechanical ventilation (TMV) is performed in amyotrophic lateral sclerosis (ALS) patients with a respiratory failure or when the non-invasive ventilation (NIV) is no longer effective. We evaluated the clinical characteristics and survival of a cohort of tracheostomized ALS patients, followed in a single ALS Clinical Center. Methods: Between 2001 and 2010, 87 out of 279 ALS patients were submitted to TMV. Onset was spinal in 62 and bulbar in 25. After tracheostomy, most patients were followed up through telephone interviews to caregivers. A complete survival analysis could be performed in fifty-two TMV patients. Results: 31.3% ALS patients underwent tracheostomy, with a male prevalence (M/F=1.69) and a median age of 61 years (interquartile range=47–66). After tracheostomy, nearly all patients were under home care. TMV ALS patients were more likely than non-tracheostomized (NT) patients to be implanted with a PEG device, although the bulbar-/spinal-onset ratio did not differ between the two groups. Kaplan–Meyer analysis showed that tracheostomy increases median survival (TMV, 47 months vs NT, 31 months, p=0.008), with the greatest effect in patients younger than 60 at onset (TMV≤60 years, 57.5 months vs NT≤60 years, 38.5 months, p=0.002). Conclusions: TMV is increasingly performed in ALS patients. Nearly all TMV patients live at home and most of them are fed through a PEG device. Survival after tracheostomy is generally increased, with the stronger effect in patients younger than 60. This survival advantage is apparently lost when TMV is performed in patients older than 60. The results of this study might be useful for the decision-making process of patients and their families about this advanced palliative care

    Qualitative analysis of determinants of measles, mumps, rubella vaccine uptake in European parents

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    Background Parental concerns about measles, mumps and rubella (MMR) vaccination negatively influence decision to vaccinate their children, this leading to the recently reported vaccine coverage drop in Europe. The ESCULAPIO project, funded by the Italian National Centre for Disease Prevention and Control of the Ministry of Health (CCM), is investigating the main factors underlying decisions on vaccinations, in order to implement targeted campaigns and plan effective strategies. Methods A systematic literature review was carried out on studies describing the determinants underlying MMR vaccination uptake in European parents. Results A total of 45 studies were included in the analysis. The most common factors related with MMR vaccine uptake were knowledge, beliefs, perceptions on vaccines and diseases, reported in 44,4% of the articles. Parents showed doubts on vaccine efficacy, safety, side effects, while in other studies positive beliefs and perceptions were reported. Attitudes/ behaviours were often determinants of the uptake as well as demographic factors (40%). While higher no. of children in the household, lower income, temporary or lacking employment, and non-regular marital status were generally a barrier for vaccination, education level and house tenure were contradictory. Information source/advice and influence or trust of other people, institutions, media were often reported (31,1% and 17,8% respectively), but a clear direction was not showed. Conclusions These preliminary findings showed that communication strategies should provide parents with clear messages on vaccines and preventable infectious diseases, in order to build right knowledge and create correct beliefs and behaviours. Communication should be addressed mainly to more disadvantaged, larger and non-regular families. A quantitative analysis is been currently carrying out and will provide more information on the direction of the effect of the different factor

    Influenza vaccine effectiveness among high-risk groups: a systematic literature review and metaanalysis of case-control and cohort studies

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    Vaccination represents the most effective intervention to prevent infection, hospitalization and mortality due to influenza. This meta-analysis quantifies data reporting influenza vaccine effectiveness (VE) on influenza visits and hospitalizations of case-control and cohort studies among high-risk groups. A systematic literature review including original articles published between 2007 and 2016, using a protocol registered on Prospero with No. 42017054854, and a meta-analysis were conducted. For three high-risk groups (subjects with underlying health conditions, pregnant women and health care workers) only a qualitative evaluation was carried out. The VE quantitative analysis demonstrated a clear significant overall effect of 39% (95%CI: 32%-46%) for visits and 57% (95%CI: 30%-74%) for hospitalization among children. Considering the elderly influenza VE had a clear effect of 25% (95%CI: 6%-40%) for visits and 14% (95%CI: 7%-21%; p<0.001) for hospitalization. This study showed the high VE of influenza vaccination among high-risk groups, representing a tool for public health decision-makers to develop evidence-based preventive interventions to avoid influenza outcome
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