6,185 research outputs found
Development and demonstration of flueric sounding rocket motor ignition
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
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
Determinants associated with obesity and physical activity in the public and private schools of the city of palermo
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
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 ~cm was
observed on time scales of months. We also find that the photon index of the
underlying power law continuum () 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.
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
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
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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