Large and Almost Maximal Neutrino Mixing within the Type II See-Saw Mechanism

Within the type II see-saw mechanism the light neutrino mass matrix is given by a sum of a direct (or triplet) mass term and the conventional (type I) see-saw term. Both versions of the see-saw mechanism explain naturally small neutrino masses, but the type II scenario offers interesting additional possibilities to explain large or almost maximal or vanishing mixings which are discussed in this paper. We first introduce ``type II enhancement'' of neutrino mixing, where moderate cancellations between the two terms can lead to large neutrino mixing even if all individual mass matrices and terms generate small mixing. However, nearly maximal or vanishing mixings are not naturally explained in this way, unless there is a certain initial structure (symmetry) which enforces certain elements of the matrices to be identical or related in a special way. We therefore assume that the leading structure of the neutrino mass matrix is the triplet term and corresponds to zero U_{e3} and maximal theta_{23}. Small but necessary corrections are generated by the conventional see-saw term. Then we assume that one of the two terms corresponds to an extreme mixing scenario, such as bimaximal or tri-bimaximal mixing. Deviations from this scheme are introduced by the second term. One can mimic Quark-Lepton Complementarity in this way. Finally, we note that the neutrino mass matrix for tri-bimaximal mixing can be -- depending on the mass hierarchy -- written as a sum of two terms with simple structure. Their origin could be the two terms of type II see-saw.Comment: 25 pages. Comments and references added, to appear in JHE

Towards an understanding of neuroscience for science educators

Advances in neuroscience have brought new insights to the development of cognitive functions. These data are of considerable interest to educators concerned with how students learn. This review documents some of the recent findings in neuroscience, which is richer in describing cognitive functions than affective aspects of learning. A brief overview is presented here of the techniques used to generate data from imaging and how these findings have the possibility to inform educators. There are implications for considering the impact of neuroscience at all levels of education – from the classroom teacher and practitioner to policy. This relatively new cross-disciplinary area of research implies a need for educators and scientists to engage with each other. What questions are emerging through such dialogues between educators and scientists are likely to shed light on, for example, reward, motivation, working memory, learning difficulties, bilingualism and child development. The sciences of learning are entering a new paradigm

Recommendations for analytical antiretroviral treatment interruptions in HIV research trials: report of a consensus meeting

Analytical antiretroviral treatment interruption (ATI) is an important feature of HIV research, seeking to achieve sustained viral suppression in the absence of antiretroviral therapy (ART) when the goal is to measure effects of novel therapeutic interventions on time to viral load rebound or altered viral setpoint. Trials with ATIs also intend to determine host, virological, and immunological markers that are predictive of sustained viral control off ART. Although ATI is increasingly incorporated into proof-of-concept trials, no consensus has been reached on strategies to maximise its utility and minimise its risks. In addition, differences in ATI trial designs hinder the ability to compare efficacy and safety of interventions across trials. Therefore, we held a meeting of stakeholders from many interest groups, including scientists, clinicians, ethicists, social scientists, regulators, people living with HIV, and advocacy groups, to discuss the main challenges concerning ATI studies and to formulate recommendations with an emphasis on strategies for risk mitigation and monitoring, ART resumption criteria, and ethical considerations. In this Review, we present the major points of discussion and consensus views achieved with the goal of informing the conduct of ATIs to maximise the knowledge gained and minimise the risk to participants in clinical HIV research

An in vitro model for the study of phagocytosis of damaged hepatocytes by rat Kupffer cells

AIMS/BACKGROUND: One function of Kupffer cells is the phagocytosis of nonviable hepatocytes. Our aims were to develop a model for phagocytosis of damaged hepatocytes by rat Kupffer cells in vitro, and to characterise prostaglandin E2 (PGE2), prostacyclin (PGI), and tumour necrosis factor-alpha (TNF) production in this model. METHODS: Kupffer cells were incubated alone or with damaged hepatocytes for up to 18 h, then washed and cultured for up to 66 h. To compare mediator responses produced during inert particle phagocytosis, Kupffer cells were also incubated with latex beads. RESULTS: Phagocytic uptake of hepatocyte debris was confirmed in at least 50% of Kupffer cells. A dissociation between TNF and PGI responses was found for both latex beads and damaged hepatocytes, such that a TNF secretory response was not triggered by either stimulus whereas PGI production was increased for both. Although phagocytosis of beads increased PGE2 production, phagocytosis of hepatocytes did not. CONCLUSIONS: Phagocytosis of damaged hepatocytes by Kupffer cells results in the production of PGI but not PGE2 or TNF

Seasonal influenza vaccination predicts pandemic H1N1 vaccination uptake among healthcare workers in three countries

The aim of this study was to identify the common barriers and facilitators for acceptance of pandemic influenza vaccination across different countries. This study utilized a standardized, anonymous, self-completed questionnaire-based survey recording the demographics and professional practice, previous experience and perceived risk and severity of influenza, infection control practices, information of H1N1 vaccination, acceptance of the H1N1 vaccination and reasons of their choices and opinions on mandatory vaccination. Hospital-based doctors, nurses and allied healthcare workers in Hong Kong (HK), Singapore (SG) and Leicester, United Kingdom (UK) were recruited. A total of 6318 (HK: 5743, SG: 300, UK: 275) questionnaires were distributed, with response rates of 27.1% (HK), 94.7% (SG) and 94.5% (UK). The uptake rates for monovalent 2009 pandemic H1N1 vaccine were 13.5% (HK), 36.2% (SG) and 41.3% (UK). The single common factor associated with vaccine acceptance across all sites was having seasonal influenza vaccination in 2009. In UK and HK, overestimation of side effect reduced vaccination acceptance; and fear of side effect was a significant barrier in all sites. In HK, healthcare workers with more patient contact were more reluctant to accept vaccination. Drivers for vaccination in UK and HK were concern about catching the infection and following advice from health authority. Only a small proportion of respondents agreed with mandatory pandemic influenza vaccination (HK: 25% and UK: 42%), except in Singapore where 75.3% were in agreement. Few respondents (&lt;5%) chose scientific publications as their primary source of information, but this group was more likely to receive vaccination. The acceptance of pandemic vaccine among healthcare workers was poor (13-41% of respondents). Breaking barriers to accept seasonal influenza vaccination should be part of the influenza pandemic preparedness plan. Mandatory vaccination even during pandemic is likely to arouse substantial discontent.<br/