Panel 6 : Vaccines

Objective. To review the literature on progress regarding (1) effectiveness of vaccines for prevention of otitis media (OM) and (2) development of vaccine antigens for OM bacterial and viral pathogens. Data Sources. PubMed database of the National Library of Science. Review Methods. We performed literature searches in PubMed for OM pathogens and candidate vaccine antigens, and we restricted the searches to articles in English that were published between July 2011 and June 2015. Panel members reviewed literature in their area of expertise. Conclusions. Pneumococcal conjugate vaccines (PCVs) are somewhat effective for the prevention of pneumococcal OM, recurrent OM, OM visits, and tympanostomy tube insertions. Widespread use of PCVs has been associated with shifts in pneumococcal serotypes and bacterial pathogens associated with OM, diminishing PCV effectiveness against AOM. The 10-valent pneumococcal vaccine containing Haemophilus influenzae protein D (PHiD-CV) is effective for pneumococcal OM, but results from studies describing the potential impact on OM due to H influenzae have been inconsistent. Progress in vaccine development for H influenzae, Moraxella catarrhalis, and OM-associated respiratory viruses has been limited. Additional research is needed to extend vaccine protection to additional pneumococcal serotypes and other otopathogens. There are likely to be licensure challenges for protein-based vaccines, and data on correlates of protection for OM vaccine antigens are urgently needed. Implications for Practice. OM continues to be a significant health care burden globally. Prevention is preferable to treatment, and vaccine development remains an important goal. As a polymicrobial disease, OM poses significant but not insurmountable challenges for vaccine development.Peer reviewe

Propagation of leaky MHD waves at discontinuities with tilted magnetic field

We investigate the characteristics of magneto-acoustic surface waves propagating at a single density interface, in the presence of an inclined magnetic field. For linear wave propagation, the dispersion relation is obtained and analytical solutions are derived for small inclination angle. The inclination of the field renders the frequency of the waves complex, where the imaginary part describes wave attenuation, due to lateral energy leakage

The role of mentoring in supporting novice English language teachers in Hong Kong

This article reports on qualitative case study research into the experience and support of four novice English language teachers in Hong Kong (HK). It describes their perceived experience and socialisation, particularly with regard to the induction and mentoring support they receive during the first year of teaching. While the benefits of different forms of induction support (mentoring in particular) have been established, few studies have focused on specific factors that affect the perceived effectiveness of mentoring, from the point of view of both the mentors and the mentees. The current study therefore breaks new ground in investigating the perspectives of different stakeholders in the mentoring process. What is more, the majority of research reports the nature of the first year of teaching in one snapshot, often not paying attention to the professional development and changes throughout the year. This study follows a group of novice language teachers for the whole of their first year in teaching

Improved Performance of Polymer Electrolyte Membrane Fuel Cells with Modified Microporous Layer Structures

A possible method to improve membrane humidity conditions in polymer electrolyte membrane fuel cells and, therefore, the cell performance is the optimization of microporous layer MPL structures. In this work, water transport in modified MPL materials in polymer electrolyte membrane fuel cells PEMFCs was investigated by in amp; 8197;operando synchrotron X ray tomography. Three different types of MPLs are compared A reference standard MPL material, an MPL material with a special wavy structure, and an MPL with randomly distributed holes. We found a strong impact of the modified MPL structure on the water distribution at operating temperatures of 40 and 55 amp; 8201; C and an increase of cell performance up to 14 amp; 8201; compared to the reference cell. We assume the water distribution at the membrane to be responsible for the performance increase and provide a detailed discussion

X ray Tomographic Investigation of Water Distribution in Polymer Electrolyte Membrane Fuel Cells with Different Gas Diffusion Media

In this study, water transport in polymer electrolyte membrane fuel cells PEMFCs is investigated by synchrotron X ray tomography. The measurement technique is used to reveal the relationship between the structure of the gas diffusion media GDM and the water distribution. It is shown how the water distribution and transport is visualized and quantitatively analyzed. We present investigations on three different GDM A GDM with a modified microporous layer MPL , a thick GDM with limited back diffusion and a reference materia

The Influence of Porous Transport Layer Modifications on the Water Management in PEM Fuel Cells

In this study, the influence of modifications of the porous transport layer PTL on the water management in PEM fuel cells is investigated. Laser perforation and milling are used to locally remove either the whole PTL or only the micro porous layer in the PTL. The changed dynamics and steady state distribution of the liquid water are visualized both in plane and through plane using synchrotron radiography and ESEM liquid water imaging. The observed effects are correlated with in situ performance characteristics, pre assembly and post mortem analysis to examine on the beneficial and obstructive effects of the modifications. The pre assembly analysis reveals that laser perforation results in PTFE loss in nearby regions. Hydrophilic regions around the holes are observed in both ESEM liquid water visualization and synchrotron radiography which results in a good performance at dry conditions but serious flooding at high humidification conditions. Machined perforations show beneficial effects in the in situ performance characteristics at high humidification conditions. A draining of the vicinity of the perforations is observed which results in an improved oxygen diffusivity. Water balancing and synchrotron visualization indicate that under the analyzed operating conditions the MPL increases the humidification of the Membrane Electrode Assembly on the one hand but creates an additional diffusion barrier by liquid water in the interface between the cathode catalyst layer and the MPL on the other han

The Influence of Porous Transport Layer Modifications on the Water Management in PEM Fuel Cells

In this study, the influence of modifications of the porous transport layer PTL on the water management in PEM fuel cells is investigated. Laser perforation and milling are used to locally remove either the whole PTL or only the micro porous layer in the PTL. The changed dynamics and steady state distribution of the liquid water are visualized both in plane and through plane using synchrotron radiography and ESEM liquid water imaging. The observed effects are correlated with in situ performance characteristics, pre assembly and post mortem analysis to examine on the beneficial and obstructive effects of the modifications. The pre assembly analysis reveals that laser perforation results in PTFE loss in nearby regions. Hydrophilic regions around the holes are observed in both ESEM liquid water visualization and synchrotron radiography which results in a good performance at dry conditions but serious flooding at high humidification conditions. Machined perforations show beneficial effects in the in situ performance characteristics at high humidification conditions. A draining of the vicinity of the perforations is observed which results in an improved oxygen diffusivity. Water balancing and synchrotron visualization indicate that under the analyzed operating conditions the MPL increases the humidification of the Membrane Electrode Assembly on the one hand but creates an additional diffusion barrier by liquid water in the interface between the cathode catalyst layer and the MPL on the other han

Investigation of water transport dynamics in polymer electrolyte membrane fuel cells based on high porous micro porous layers

In this study, synchrotron X ray imaging is used to investigate the water transport inside newly developed GDM gas diffusion medium in polymer electrolyte membrane fuel cells. Two different measurement techniques, namely in situ radiography and quasi in situ tomography were combined to reveal the relationship between the structure of the MPL microporous layer , the operation temperature and the water flow. The newly developed MPL is equipped with randomly arranged holes. It was found that these holes strongly influence the overall water transport in the whole adjacent GDM. The holes act as nuclei for water transport paths through the GDM. In the future, such tailored GDMs could be used to optimize the efficiency and operating conditions of polymer electrolyte membrane fuel cell