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Influenza vaccination of elderly individuals is recommended worldwide. Our aim was to review the evidence of efficacy and effectiveness of influenza vaccines in individuals aged 65 years or older. We searched five electronic databases to December, 2004, in any language, for randomised (n=5), cohort (n=49), and case-control (n=10) studies, assessing efficacy against influenza (reduction in laboratory-confirmed cases) or effectiveness against influenza-like illness (reduction in symptomatic cases). We expressed vaccine efficacy or effectiveness as a proportion, using the formula VE=1–relative risk (RR) or VE*=1–odds ratio (OR). We analysed the following outcomes: influenza, influenza-like illness, hospital admissions, complications, and deaths. In homes for elderly individuals (with good vaccine match and high viral circulation) the effectiveness of vaccines against influenza-like illness was 23% (95% CI 6–36) and non-significant against influenza (RR 1·04, 0·43–2·51). Well matched vaccines prevented pneumonia (VE 46%, 30–58) and hospital admission (VE 45%, 16–64) for and deaths from influenza or pneumonia (VE 42%, 17–59), and reduced all-cause mortality (VE 60%, 23–79). In elderly individuals living in the community, vaccines were not significantly effective against influenza (RR 0·19, 0·02–2·01), influenza-like illness (RR 1·05, 0·58–1·89), or pneumonia (RR 0·88, 0·64–1·20). Well matched vaccines prevented hospital admission for influenza and pneumonia (VE 26%, 12–38) and all-cause mortality (VE 42%, 24–55). After adjustment for confounders, vaccine performance was improved for admissions to hospital for influenza or pneumonia (VE* 27%, 21–33), respiratory diseases (VE* 22%, 15–28), and cardiac disease (VE* 24%, 18–30), and for all-cause mortality (VE* 47%, 39–54). In long-term care facilities, where vaccination is most effective against complications, the aims of the vaccination campaign are fulfilled, at least in part. However, according to reliable evidence the usefulness of vaccines in the community is modest.

Use of antivirals is recommended for the control of seasonal and pandemic influenza. Our aim was to review the evidence of efficacy, effectiveness, and safety of registered antivirals against naturally occurring influenza in healthy adults. We searched various Databases to October, 2005, and contacted manufacturers and corresponding authors. We included randomised controlled trials comparing prophylactic (n=27) or treatment (n=27) efficacy against symptomatic or asymptomatic influenza. We did a meta-analysis and expressed prophylactic efficacy as a proportion (1–relative risk [RR]). For treatment trials, because of inconsistent and non-standardised reporting, we expressed continuous outcomes either as means or as hazard ratios. We included 51 reports of 52 randomised controlled trials. Amantadine prevented 61% (95% CI 35–76) of influenza A cases and 25% (13–36) of cases of influenza-like illness, but caused nausea (OR 2·56, 1·37–4·79), insomnia and hallucinations (2·54, 1·50–4·31), and withdrawals because of adverse events (2·54, 1·60–4·06). There was no effect on asymptomatic cases (RR 0·85, 0·40–1·80). In treatment, amantadine significantly shortened duration of fever compared with placebo (by 0·99 days, −1·26 to −0·71), but had no effect on nasal shedding of influenza A viruses (0·93, 0·71–1·21). The fewer data for rimantadine showed comparable effects. In prophylaxis, compared with placebo, neuraminidase inhibitors have no effect against influenza-like illness (1·28, 0·45–3·66 for oral oseltamivir 75 mg daily, 1·51, 0·77–2·95 for inhaled zanamivir 10 mg daily). Higher doses appear to make no difference. The efficacy of oral oseltamivir 75 mg daily against symptomatic influenza is 61% (15–82), or 73% (33–89) at 150 mg daily. Inhaled zanamivir 10 mg daily is 62% efficacious (15–83). Neither neuraminidase inhibitor appeared effective against asymptomatic influenza. Oseltamivir induces nausea (OR 1·79, 1·10–2·93), especially at higher prophylactic doses (2·29, 1·34–3·92). Oseltamivir in a post-exposure prophylaxis role has a protective efficacy of 58·5% (15·6–79·6) for households and from 68% (34·9–84·2) to 89% (67–97) in contacts of index cases. In influenza cases, compared with placebo the hazard ratios for time to alleviation of symptoms were 1·33, 1·29–1·37 for zanamivir; 1·30, 1·13–1·50 for oseltamivir provided medication was started within 48 h of symptom onset. Viral nasal titres were significantly diminished by both drugs (weighted mean difference −0·62, −0·82 to −0·41). Oseltamivir at 150 mg daily was effective in preventing lower respiratory tract complications in influenza cases (OR 0·32, 0·18–0·57). We could find no credible data on the effects of oseltamivir on avian influenza. The use of amantadine and rimantadine should be discouraged. Because of their low effectiveness, neuraminidase inhibitors should not be used in seasonal influenza control and should only be used in a serious epidemic or pandemic alongside other public-health measures.

Objective To review systematically the evidence of effectiveness of physical interventions to interrupt or reduce the spread of respiratory viruses.Data sources Cochrane Library, Medline, OldMedline, Embase, and CINAHL, without restrictions on language or publication.Data selection Studies of any intervention to prevent the transmission of respiratory viruses (isolation, quarantine, social distancing, barriers, personal protection, and hygiene). A search of study designs included randomised trials, cohort, case-control, crossover, before and after, and time series studies. After scanning of the titles, abstracts and full text articles as a first filter, a standardised form was used to assess the eligibility of the remainder. Risk of bias of randomised studies was assessed for generation of the allocation sequence, allocation concealment, blinding, and follow-up. Non-randomised studies were assessed for the presence of potential confounders and classified as being at low, medium, or high risk of bias.Data synthesis 58 papers of 59 studies were included. The quality of the studies was poor for all four randomised controlled trials and most cluster randomised controlled trials; the observational studies were of mixed quality. Meta-analysis of six case-control studies suggested that physical measures are highly effective in preventing the spread of severe acute respiratory syndrome: handwashing more than 10 times daily (odds ratio 0.45, 95% confidence interval 0.36 to 0.57; number needed to treat=4, 95% confidence interval 3.65 to 5.52), wearing masks (0.32, 0.25 to 0.40; NNT=6, 4.54 to 8.03), wearing N95 masks (0.09, 0.03 to 0.30; NNT=3, 2.37 to 4.06), wearing gloves (0.43, 0.29 to 0.65; NNT=5, 4.15 to 15.41), wearing gowns (0.23, 0.14 to 0.37; NNT=5, 3.37 to 7.12), and handwashing, masks, gloves, and gowns combined (0.09, 0.02 to 0.35; NNT=3, 2.66 to 4.97). The combination was also effective in interrupting the spread of influenza within households. The highest quality cluster randomised trials suggested that spread of respiratory viruses can be prevented by hygienic measures in younger children and within households. Evidence that the more uncomfortable and expensive N95 masks were superior to simple surgical masks was limited, but they caused skin irritation. The incremental effect of adding virucidals or antiseptics to normal handwashing to reduce respiratory disease remains uncertain. Global measures, such as screening at entry ports, were not properly evaluated. Evidence was limited for social distancing being effective, especially if related to risk of exposure—that is, the higher the risk the longer the distancing period.Conclusion Routine long term implementation of some of the measures to interrupt or reduce the spread of respiratory viruses might be difficult. However, many simple and low cost interventions reduce the transmission of epidemic respiratory viruses. More resources should be invested into studying which physical interventions are the most effective, flexible, and cost effective means of minimising the impact of acute respiratory tract infections.

We aimed to assess evidence of efficacy and effectiveness of live attenuated and inactivated influenza vaccines in children up to 16 years of age. We searched the Cochrane Library, MEDLINE, EMBASE Biological Abstracts, and Science Citation Index to June, 2004, in any language, and contacted vaccine manufacturers and authors of relevant studies to identify additional data. We included randomised, cohort, and case-control studies comparing efficacy of vaccines against influenza (reduction in laboratory-confirmed cases), effectiveness of vaccines against influenza-like illness (reduction in symptomatic cases), or both, with placebo or no intervention. We analysed the following outcomes: influenza, influenza-like illness, admissions, school absences, complications, and secondary transmission. We included 14 randomised controlled trials, eight cohort studies, one case-control study, and one randomised controlled trial of intraepidemic use of the vaccines. Live attenuated influenza vaccines had 79% efficacy and 38% effectiveness in children older than 2 years compared with placebo or no immunisation. Inactivated vaccines had lower efficacy (65%) than live attenuated vaccines, and in children aged 2 years or younger they had similar effects to placebo. Effectiveness of inactivated vaccines was about 28% in children older than 2 years. Vaccines were effective in reducing long school absences (relative risk 0·14 [95% CI 0·07–0·27]). Studies assessing the effects of vaccines against secondary cases, lower-respiratory tract disease, acute otitis media, and hospital stay suggested no difference with placebo or standard care, but lacked statistical power. Influenza vaccines (especially two-dose live attenuated vaccines) are efficacious in children older than 2 years. Efficacy and effectiveness of the vaccines differed strikingly. Only two small studies assessed the effects of influenza vaccines on hospital admissions and no studies assessed reductions in mortality, serious complications, and community transmission of influenza. If influenza immunisation in children is to be recommended as public-health policy, large-scale studies assessing such important outcomes and undertaking direct comparisons of vaccines are urgently needed.

PARSIFAL is a software tool originally implemented to reproduce the response of a triple-GEM interacting with a charged particle, which describes the main physical processes with a parametrization. Reliable software as GARFIELD++ is widely used to simulate a gaseous detector with great accuracy, but it is CPU-time consuming. The implementation of PARSIFAL was driven by the need to reduce the processing time, while maintaining the precision of a full simulation. The software is initialized with parameters extracted from a GARFIELD++ simulation, run only once. Then, PARSIFAL can be run independently to provide a reliable simulation by sampling from a set of functions which describe the physical effects and depend on the input parameters. The simulation of the triple-GEM was tuned on experimental results from a testbeam. Recently, PARSIFAL was extended to the μ-RWELL technology, with the implementation of the charge dispersion effect generated by the resistive layer. A fine tuning of the simulation for the μ-RWELL is ongoing, following a strategy similar to the one validated for the triple-GEM, with a special attention to the tuning of the resistivity of the resistive layer. An illustration of the general code, setting the focus on this latest implementation will be described.

Tip leakage vortex cavitation in axial hydro-turbines may cause erosion, noise and vibration. Damage due to cavitation can be found at the tip of the runner blades on the low pressure side and the discharge ring. In some cases, the erosion follows an oscillatory pattern that is related to the number of guide vanes. That might suggest that a relationship exists between the flow through the guide vanes and the tip vortex cavitating core that induces this kind of erosion. On the other hand, it is known that air injection has a beneficial effect on reducing the damage by cavitation. In this paper, a methodology to identify the interaction between guide vanes and tip vortex cavitation is presented and the effect of air injection in reducing this particular kind of erosion was studied over a range of operating conditions on a Kaplan scale model. It was found that air injection, at the expense of slightly reducing the efficiency of the turbine, mitigates the erosive potential of tip leakage cavitation, attenuates the interaction between the flow through the guide vanes and the tip vortex and decreases the level of vibration of the structural components.

In order to prevent a turbine to reach its runaway speed when load rejection occurs, an emergency closing system must be devised in case the regulation system fails. For Kaplan turbines, fixed wheel gates located in the turbine intake or in the draft tube outlet are usually employed. Gates of this type are move by gravity and the closing velocity is controlled by gantry cranes. The closing maneuver is complex due to the high flow rates inherent to runaway conditions and the rotational deceleration during the gate’s closing time. Research on this topic is scarce and limited, and numerical studies are usually clouded by uncertainties concerning the setting of proper boundary conditions. In this work, the closing maneuver of the emergency fixed wheel gates at the intake of a Kaplan turbine was studied with CFD two-phase transient simulation. The software used was ANSYS CFX, that solves unsteady Navier-Stokes equations (URANS) by means of the finite volume method. The simulated domain includes a 2D case from one of the span of the semi-spiral casing and a 3D case of a complete span. Two types of simulation were considered, namely: quasi-steady state, where the position of the gate is fixed; and full transient state, where the gate movement was modelled by an immersed solid model. In search of the optimum model layout with its set of boundary conditions, numerical results were compared and validated against experiments performed on a physical scale model in accordance with IEC 60193 norms for several turbulence models. Results show that the pull-up force on the gate increases as it is being closed. Analysis of pressure fluctuation at different points of the gate suggest that the main frequency component is the vortex shedding of the gate lip.

Thanks to their ability to adjust automatically the guide vane and runner blades position, the use of Kaplan turbines is advantageous compared to other types in terms of power regulation, as a high efficiency can be attained over a wide range of head and power. However, such features have a cost of a more complex design of the components inside the hub and the main shaft. The number of daily movements of all these components, which is linked to the required power and frequency regulation, leads to wearing and fatigue in the long term. Therefore, the replacement and reparation of components are regular maintenance tasks which, on some occasions, might entail the dismantling of the turbine and the generator when some key hub components fails. In the face of such events, a cost-benefit-based decision must be made concerning to whether repair the turbine to recover its functionality or to operate the Kaplan turbine in propeller mode. In propeller mode, the turbine can operate at on-cam condition for a single load for any given head. For loads other than the corresponding to on-cam condition, an acceptable hydraulic behaviour is not guaranteed, since such use is usually not contemplated in acceptance tests. Therefore, pressure fluctuation due to vortex rope development, cavitation, power instability and structural vibration may arise at loads other than the corresponding to on cam operation. One of the main issues that limits the operation range is the generated power oscillation due to partial load vortex development. This paper presents numerical investigations focusing in this phenomenon. The computational domain includes guide vanes, runner and draft tube. Also, a simplified draft tube consisting in a symmetrical revolution volume is explored. Measurements were performed at prototype scale at same operating conditions and pressure fluctuations, power generation, vibrations and sound emission were recorded. These measurements are then shown and compared with CFD results.

Emergency gates are the last link in the chain of safety of turbo-groups in case of distributor failure, safeguarding the power station from severe damage. These gates can be located at the turbine intake or at the outlet of the draft tube and can be controlled by gantry cranes or hoist hydraulic cylinders. Gates must descend with high flow for a short time to prevent the turbine from spinning at runaway velocity for periods longer than admissible, as that would entail the rise of uplift and downpull forces that may jeopardize their stability. Indeed, at the prototype scale, the closing maneuver entails a certain risk, because of which it is usually tested avoiding extreme conditions. In this work, the operation of emergency gates was tested against more severe conditions on a reduced-scale physical model. The case study involves three emergency gates controlled by gantry cranes and located at the intake of a large Kaplan turbine which underwent high levels of vibration when operated at prototype scale. Model tests were aimed at detecting and quantifying hydraulic phenomena that might emerge during operation with an eye on the proposal of alternative designs. Unlike most tests of this sort, the experimental setup includes the runner of the turbine assembled on a test rig, which allows for a more realistic flow distribution along the vanes during the gate closure under runaway conditions. Steady state tests were carried out under runaway conditions, while stems of servomotors enabled the regulation of the position of the gate. Downpull forces were found to start at 12 % of the gate opening. Flow asymmetry was observed, gate on the left of the semi-spiral casing being the most affected by higher flow velocities. The runner vortex rope frequency was measured also at gate lip for some particular conditions.

Francis turbines operating at high load conditions produce a typical flow pattern in the draft tube cone characterized by the presence of an axisymmetric central vortex. This central cavity could become unstable, generating synchronic pressure pulsations, usually called self-excited oscillations, which propagate into the whole machine. The on-set and size of the central vortex cavity depend on the geometry of the runner and draft tube and on the operating point as well. Numerical flow simulations and model tests allow for the characterization of the different flow patterns induced by each particular Francis turbine design and, when studied in combination with the hydraulic system, including the intake and penstock, could predict the prototype hydraulic behavior for the complete operation zone. The present work focuses the CFD simulation on the development and dynamic behavior of the central axisymmetric vortex for a medium-head Francis turbine operating at high load conditions. The CFD simulations are based in two-phase transient calculations. Oscillation frequencies against its cavity volume development were obtained and good correlation was found with experimental results.