The predictive value of a QuantiFERON conversion in the development of active tuberculosis disease in adolescents

This study is an extension of a prospective epidemiological study of TB disease and infection in adolescents in the Worcester and surrounding areas in the Western Cape carried out from 2005 to 2009, in which 6363 participants were enrolled from local public schools. In this follow-on study, a subset of adolescents who were identified to have converted their QFT status during the original study will be followed up and observed for the occurrence of active TB disease over a period of two years. A similar sized, random sample of participants identified to have a QFT status that remained negative throughout the original study will be used as the control group

Flavor Symmetry and Vacuum Aligned Mass Textures

The mass matrix forms of quarks and leptons are discussed in theory with permutation flavor symmetry. The structure of scalar potential is analyzed in case that electroweak doublet Higgs fields have non-trivial flavor symmetry charges. We find that realistic forms of mass matrices are obtained dynamically in the vacuum of the theory, where some of Higgs bosons have vanishing expectation values which lead to vanishing elements in quark and lepton mass matrices. Mass textures are realized in the true vacuum and their positions are controlled by flavor symmetry. An interesting point is that, due to the flavor group structure, the up and down quark mass matrices are automatically made different in the vacuum, which lead to non-vanishing generation mixing. It is also discussed that flavor symmetry is needed to be broken in order not to have too light scalars. The lower bounds of Higgs masses are derived from the experimental data of flavor-changing rare processes such as the neutral K meson mixing.Comment: 30pages, 2figures, some discussions are added, one reference is adde

Influence of food safety culture on food handler behaviour and food safety performance of food processing organisations

  Food safety continues to be a challenge in many food companies especially in emerging economies, which are confronted with multiple issues in both the internal and external company environment. Previous efforts to improve food safety performance have been hinged on traditional and technical-oriented approaches such as sampling, testing, inspections, food safety management systems (FSMS) and auditing, which have proven to be not always adequate evidenced by inconsistencies in food safety performance. To enhance food safety performance in food companies, researchers proposed to look beyond these traditional and technical-oriented approaches towards a more integrated approach and suggested the adoption and strengthening of a positive and pro-active food safety culture (FS-culture). FS-culture encompasses a company’s technological and organisational conditions, characteristics of the individuals within the company and the company’s environment, in addition to the existing FSMS. However, FS-culture research is still developing when compared with other culture research domains such as organisational and safety culture. Moreover, there are still knowledge gaps on what FS-culture entails, its measurement, its relationship with food safety performance and how it could be improved. This thesis, therefore, focused on understanding how an organisation’s FS-culture influences food safety and hygiene-related behaviour and food safety performance of an organisation. The literature review presented in chapter 2 identified determinants for conducting FS-culture research. Findings revealed that numerous factors transcending different disciplines are interlinked and as such a systems approach is required to assess an organisation’s FS-culture. The review showed that several elements i.e. individual, group, organisational, technological and company environment characteristics are necessary to evaluate FS-culture, and its influence on food handler behaviour and food safety performance. Moreover, the research suggested that a company’s food safety risks should be considered and to recognise the hierarchical levels as well. The research also suggested defining measurable indicators, development of classification systems, and the use of a triangulated methodology. The resultant determinants provided a basis upon which further FS-culture research could be built on. As a result of these findings, elements suggested in the review were validated in chapter 3 as they enabled an understanding of the prevailing FS-culture of the companies investigated. Moreover, a mixed-methods approach was presented to assess the prevailing FS-culture, with dairy food companies in Zimbabwe as a case study. The methods included: microbial analysis to assess the microbial safety, observations to evaluate actual behaviour, card-aided interviews to assess organisational and technological enabling conditions, questionnaires and storytelling to collect data on employee characteristics, and document analysis to get insight into the microbial safety performance and actual behaviour. Results showed that a mixed-methods approach is suitable in FS-culture assessments due to the method triangulation, which could potentially increase the validity of the research findings. Both the FS-culture elements and the mixed-methods approach enabled the prevailing FS-culture to be distinguished into identified classification levels (reactive, active, proactive) further enhancing their validity. Based on the empirical study, a FS-culture research framework was further developed in Chapter 4, to concurrently assess the prevailing FS-culture of companies differing in product riskiness, as well as the company’s internal and external environment. The framework assessed the following factors: supportiveness of the organisational and technological enabling conditions, employee characteristics, intended and actual behaviour, food safety performance, and the internal (food safety vision, food safety programs, vulnerability of production systems) and external (national values and food safety governance) company environment. The framework was applied to Zimbabwean food companies differing in product riskiness i.e. low, medium and high-risk. Results indicated no direct relationship between product riskiness and FS-culture. However, the company environment seemed to be associated with the prevailing FS-culture. Regarding the internal environment, the vulnerability of the food production system (i.e. susceptibility to microbial contamination) seemed to influence the prevailing FS-culture. With respect to the external environment, food safety governance and national values seemed to influence the way food safety was prioritised, food safety programs were designed, and the way food handlers executed their tasks in actual practice. Chapter 5 further explored the role of the internal and external company environment on an organisation’s FS-culture, in companies operating in Greece, China, Tanzania and Zambia. Both the internal and external company environment seemed to influence the prevailing FS-culture. Companies in African countries (i.e. Tanzania and Zambia) exhibited similarities in the implementation of food safety programs, and in the national values and food safety governance when compared to Greece and China. Food safety governance was reflected in the food safety programs and supportiveness of the organisation to food safety and hygiene. Hofstede cultural dimensions i.e. uncertainty avoidance, masculinity and long vs short-term orientation, reflecting national values, were significantly statistically correlated with aspects of FS-culture such as risk perceptions, attitude and the enabling conditions. Chapter 6 discusses the overall findings in this thesis and presents a broader outlook on FS-culture from an organisational, individual and company environment perspective. Furthermore, a stepwise approach to create, improve and sustain an organisation’s FS-culture is presented. Practical implications of findings in this thesis and recommendations for further research and for the food companies studied are presented. Overall, the research presented in this thesis contributes to the existing literature on FS-culture by providing research determinants that could be useful as a basis upon which further FS-culture research can be built on. Moreover, it provides a FS-culture research framework and assessment grids that can be used for the concurrent analysis and differentiated assessment of an organisation’s prevailing FS-culture, food safety performance, and the internal and external company environment. The mixed-methods approach could enable an in-depth analysis of an organisation’s FS-culture through method-triangulation. Insights provided in this thesis could enable the identification of the prevailing FS-culture, which could be useful in designing effective interventions to create, improve, strengthen and sustain a positive FS-culture. The stepwise approach developed in this thesis could help identify improvement opportunities towards a positive and sustainable FS-culture, thereby contributing to better food safety performanc

Interest in Continuing Surgical Activity—A Necessity During the Pandemic

No Abstract

Passive transfer of modest titers of potent and broadly neutralizing anti-HIV monoclonal antibodies block SHIV infection in macaques

It is widely appreciated that effective human vaccines directed against viral pathogens elicit neutralizing antibodies (NAbs). The passive transfer of anti–HIV-1 NAbs conferring sterilizing immunity to macaques has been used to determine the plasma neutralization titers, which must be present at the time of exposure, to prevent acquisition of SIV/HIV chimeric virus (SHIV) infections. We administered five recently isolated potent and broadly acting anti-HIV neutralizing monoclonal antibodies (mAbs) to rhesus macaques and challenged them intrarectally 24 h later with either of two different R5-tropic SHIVs. By combining the results obtained from 60 challenged animals, we determined that the protective neutralization titer in plasma preventing virus infection in 50% of the exposed monkeys was relatively modest (∼1:100) and potentially achievable by vaccination

Phase-dependent preference of thermosensation and chemosensation during simultaneous presentation assay in Caenorhabditis elegans

<p>Abstract</p> <p>Background</p> <p>Multi-sensory integration is necessary for organisms to discriminate different environmental stimuli and thus determine behavior. <it>Caenorhabditis elegans </it>has 12 pairs of amphid sensory neurons, which are involved in generating behaviors such as thermotaxis toward cultivation temperature, and chemotaxis toward chemical stimuli. This arrangement of known sensory neurons and measurable behavioral output makes <it>C. elegans </it>suitable for addressing questions of multi-sensory integration in the nervous system. Previous studies have suggested that <it>C. elegans </it>can process different chemoattractants simultaneously. However, little is known about how these organisms can integrate information from stimuli of different modality, such as thermal and chemical stimuli.</p> <p>Results</p> <p>We studied the behavior of a population of <it>C. elegans </it>during simultaneous presentation of thermal and chemical stimuli. First, we examined thermotaxis within the radial temperature gradient produced by a feedback-controlled thermoregulator. Separately, we examined chemotaxis toward sodium chloride or isoamyl alcohol. Then, assays for simultaneous presentations of 15°C (colder temperature than 20°C room temperature) and chemoattractant were performed with 15°C-cultivated wild-type worms. Unlike the sum of behavioral indices for each separate behavior, simultaneous presentation resulted in a biased migration to cold regions in the first 10 min of the assay, and sodium chloride-regions in the last 40 min. However, when sodium chloride was replaced with isoamyl alcohol in the simultaneous presentation, the behavioral index was very similar to the sum of separate single presentation indices. We then recorded tracks of single worms and analyzed their behavior. For behavior toward sodium chloride, frequencies of forward and backward movements in simultaneous presentation were significantly different from those in single presentation. Also, migration toward 15°C in simultaneous presentation was faster than that in 15°C-single presentation.</p> <p>Conclusion</p> <p>We conclude that worms preferred temperature to chemoattractant at first, but preferred the chemoattractant sodium chloride thereafter. This preference was not seen for isoamyl alcohol presentation. We attribute this phase-dependent preference to the result of integration of thermosensory and chemosensory signals received by distinct sensory neurons.</p

Assessment for learning (AFL): Special Educators’ perceptions about the effectiveness of this practice for students with complex learning difficulties and disabilities (CLDD)

Assessment for learning has been hailed as an assessment practice that can improve achievement in learners. Research has proved that to be true. However, most of this research has been carried out with normally developing students and those with mild disabilities to prove its effectiveness, but there has been very little done with students with complex intellectual learning difficulties and disabilities. This study aimed to explore the effectiveness of assessment for learning in these students and the perceptions of those educators who work with them. An interpretive case study was undertaken in one school which had committed to use assessment for learning with such students. Data was collected from interviews carried out with ten participants; two senior managers, five teachers and two teacher aides. Data collection was triangulated by also reviewing documents, such as school policies, journal entries, reflection notes, teacher planning and professional development minutes. Video evidence from classroom practices was also reviewed to add to the data collected. The data analysis was informed by thematic and constant comparative strategies, which were completed using the data analysis software Nvivo. Themes, patterns and relationships were identified. Methodological triangulation enhanced the validation of the data analysis. It was perceived by the participants in this study that assessment for learning was one of the most effective ways to assist learning and enhance engagement, involvement, participation, communication and autonomy in students with complex learning difficulties and disabilities. Furthermore, it allows collaboration and partnership between the student and the teacher in the learning process. However, it was found out that for this strategy to be effective with this group of learners, adjustments, adaptations and accommodations are required to assist learners to access and navigate through the process of AFL meaningfully. Participants spent a fair amount of time exploring strategies and tools which assisted and scaffolded students in the accessing assessment for learning. This research contributed to the understanding of the use of assessment for learning with learners with complex learning difficulties and disabilities. It justifies that assessment for learning is a collaborative participatory strategy that allows students with complex learning difficulties and disabilities to take some control of their lives and shape their own destinies. It also gives insights as to why total inclusion has been hard to achieve because of the time and effort constraints it puts on mainstream teachers who are already burdened by large classes. Another significance of the study is that practice and meaning making is highly situated and therefore building teacher capacity is paramount and it takes time. The findings of this study should help policy makers, school administrators and Educational officers to understand the demands on teacher time, expertise and capacity that is required when employing assessment for learning with students with complex learning difficulties and disabilities

Growth, Yield and Fruit Quality of Tomato as Affected by Root Zone Restriction in Combination with Solar-mediated Fertigation Regime

　Plant growth and fruit development of tomato (Lycopersicon esculentum Mill. cv. House Momotaro) grown in different sized plastic pots (root zone volume, RZV, of 250, 500, 1,000 mL/plant) in combination with high or low rate of drip fertigation (HF and LF) were investigated. In the February-sown experiment, the plants were fertigated with standard to half strength of Ohtsuka-A solution in proportion to solar radiation keeping the ratio of drainage to supplied solution as 10 to 20ｵ, in 500mL- and 250mL-RZV for HF and LF, respectively. Stem and leaf growth decreased with decrease in RZV and the fertigation rate. The decreases were not significant in the distal plant part lower than the 4th inflorescence. The average fruit weight was greater in HF than LF and increased with increase in RZV only for HF. The incidence of blossom-end rot (BER) was more frequent in HF compared to LF and increased with increase in RZV only for LF. Consequently, fruit yield increased with increase in RZV for HF, but it decreased with increase in RZV for LF. Total soluble solid content (TSS) was significantly higher in LF than in HF and increased with decrease in RZV. Qualified fruits, called ‘fruit tomato’ having 8ｵ of TSS or higher, were obtained with 250 to 500mL of RZV in the successive October-sown experiment where the standard solution was supplied throughout. For ‘fruit tomato’ production with a substrate culture system, root zone restriction, in combination with solar-mediated fertigation control, can be a useful and stable stress factor, reducing shoot and fruit growth, but inducing fruit sugar accumulation and reducing BER incidence simultaneously