42 research outputs found
The Factors Which Have Resulted in Migrant Workers Being 'Essential' Workers on New Zealand Dairy Farms
Over the past decade, the dairy industry has grown in land area, number of cows, milk production and dairy exports to the point where it is New Zealand’s premier exporter. Growth has been accompanied by significant structural changes to the industry. In particular, many small, family owned and managed farms, that were characterised by high levels of selfÂÂemployment, have been replaced by largeÂÂscale ‘factory’ style, irrigated farms that depend on nonÂÂfamily, often casualized and seasonal workers, who work very long hours. Staffing these farms has been problematic and recruitment and retention have been regularly highlighted issues. Such issues have cast doubt on the social sustainability of the dairy industry. The future of the dairy industry to a large degree depends on its people. Many of these people are now migrants, who have become ‘essential’ because traditional sources of labour are inadequate. Does a dependence on migrant workers jeopardise the future stability and sustainability of dairy production? Can all stakeholders in the industry benefit from migratory staff in such a way that all parties achieve a winning outcome, as for the horticultural Recognised Seasonal Employer Scheme. A profound change in the dairy industry may be necessary to ensure that stakeholders make the effort necessary to negotiate such a multiÂÂwin outcome, which might provide a lasting rather than a temporary solution. The paper reviews the changes in the dairy farm labour force from Census data, Linked employeeÂÂemployer data (LEED) and information from the Department of Labour on temporary work permits. The risks associated with dependence on a migratory labour force are considered
Norms of Ideals in Direct Sums of Number Fields and Applications to the Circulants Problem of Olga Taussky-Todd
This thesis, 'Norms of Ideals in direct sums of number fields and applications to the circulants problem of Olga Taussky-Todd,' presents wide-ranging material in the Mathematical areas of Algebraic and Analytic Number Theory. The work, which is substantially original, is set out in three chapters which are supported by appendices. As the title suggests, the main aim is to tackle a problem which was originally posed by Olga Taussky-Todd who asked what values can be taken by the determinant of a certain type of n X n matrix with integer entries - the circulant (see [15]). Hitherto fragmentary algebraic results have been proved by M.Newman, using matrix manipulation ([5],[6]). However, for a given circulant, he gave no indication as to what proportion of integers are values. The thesis solves this problem by utilising a well-known relationship between determinants of matrix transformations and "absolute" norms of fractional ideals in a direct sum of number fields. By working appropriately in the latter structure, asymptotic methods are made available to complete the solution. A sketch of the mathematical strategy is given in the preface. The overall approach is to start at the level of great generality in Chapter 1 where, by slight modification, there is a generalisation of some extensive results published by R.W.K.Odoni in recent mathematical journals (see e.g. [12]). Subsequently there is successive specialisation down to the case of the circulant. In Chapter 2, by using standard techniques of group characters and the arithmetic of cyclotomic fields there are proved a few new results for abelian group determinants. In the final chapter there are given new elementary proofs of results for particular circulants, first presented by Newman in [5,6]. Then the methodology of the first chapter is reprised to establish the most important original result of this thesis - that "almost all" integers with appropriate 'critical' exponents are values of a given circulant
Paediatric meningitis in the conjugate vaccine era and a novel clinical decision model to predict bacterial aetiology
Objectives
The aims of this study were to assess aetiology and clinical characteristics in childhood meningitis, and develop clinical decision rules to distinguish bacterial meningitis from other similar clinical syndromes.
Methods
Children aged <16 years hospitalised with suspected meningitis/encephalitis were included, and prospectively recruited at 31 UK hospitals. Meningitis was defined as identification of bacteria/viruses from cerebrospinal fluid (CSF) and/or a raised CSF white blood cell count. New clinical decision rules were developed to distinguish bacterial from viral meningitis and those of alternative aetiology.
Results
The cohort included 3002 children (median age 2·4 months); 1101/3002 (36·7%) had meningitis, including 180 bacterial, 423 viral and 280 with no pathogen identified. Enterovirus was the most common pathogen in those aged <6 months and 10–16 years, with Neisseria meningitidis and/or Streptococcus pneumoniae commonest at age 6 months to 9 years. The Bacterial Meningitis Score had a negative predictive value of 95·3%. We developed two clinical decision rules, that could be used either before (sensitivity 82%, specificity 71%) or after lumbar puncture (sensitivity 84%, specificity 93%), to determine risk of bacterial meningitis.
Conclusions
Bacterial meningitis comprised 6% of children with suspected meningitis/encephalitis. Our clinical decision rules provide potential novel approaches to assist with identifying children with bacterial meningitis.
Funding
This study was funded by the Meningitis Research Foundation, Pfizer and the NIHR Programme Grants for Applied Research
Anti-group B Streptococcus antibody in infants born to mothers with human immunodeficiency virus (HIV) infection.
BACKGROUND: HIV-exposed uninfected infants have increased infection risk and mortality compared to HIV-unexposed infants. HIV-exposed infants may be at increased risk of invasive GBS disease due to reduced maternal antibody against GBS. METHODS: We quantified antibodies that bind to the surface of whole Group B Streptococcus (GBS) of serotypes Ia, Ib, II, III and V using novel flow cytometry assays in South African HIV-infected and non-infected mothers and their uninfected infants. Antibody-mediated complement C3b/iC3b deposition onto GBS of these serotypes was also quantified by a novel flow cytometry assay. RESULTS: Geometric mean concentration (GMC) of both surface-binding anti-GBS antibody and antibody-mediated complement deposition onto GBS were reduced in HIV-infected women (n=46) compared to HIV-uninfected women (n=58) for ST1a (surface-binding: 19.3 vs 29.3; p=0.003; complement deposition: 2.9 vs 5.3 SU/mL; p=0.003), STIb (24.9 vs 47.6; p=0.003; 2.6 vs 4.9 SU/mL; p=0.003), STII (19.8 vs 50.0; p=0.001; 3.1 vs 6.2 SU/mL; p=0.001), STIII (27.8 vs 60.1; p=0.001; 2.8 vs 5.3 SU/mL; p=0.001) and STV (121.9 vs 185.6 SU/mL; p<0.001) and in their infants for STIa (complement deposition 9.4 vs 27.0 SU/mL; p=0.02), STIb (13.4 vs 24.5 SU/mL; p=0.02), STII (14.6 vs 42.7 SU/mL; p=0.03), STIII (26.6 vs 62.7 SU/mL; p=0.03) and STV (90.4 vs 165.8 SU/mL; p=0.04). Median transplacental transfer of antibody from HIV-infected women to their infants was reduced compared to HIV-uninfected women for GBS serotypes II (0.42 [IQR 0.22-0.59] vs 1.0 SU/mL [0.42-1.66]; p<0.001), III (0.54 [0.31-1.03] vs 0.95 SU/mL [0.42-3.05], p=0.05) and V (0.51 [0.28-0.79] vs 0.75 SU/mL [0.26-2.9], p=0.04). The differences between infants remained significant at 16 weeks of age. CONCLUSIONS: Maternal HIV infection was associated with lower anti-GBS surface binding antibody concentration and antibody-mediated C3b/iC3b deposition onto GBS bacteria of serotypes Ia, Ib, II, III and V. This may render these infants more susceptible to early and late onset GBS disease
Responsible management: Engaging moral reflexive practice through threshold concepts
YesIn this conceptual paper we argue that, to date, principles of responsible management have not impacted practice as anticipated because of a disconnect between knowledge and practice. This disconnect means that an awareness of ethical concerns, by itself, does not help students take personal responsibility for their actions. We suggest that an abstract knowledge of principles has to be supplemented by an engaged understanding of the responsibility of managers and leaders to actively challenge irresponsible practices. We argue that a form of moral reflexive practice drawing on an understanding of threshold concepts is central to responsible management, and provides a gateway to transformative learning. Our conceptual argument leads to implications for management and professional education
Studies on lysolecithin in human plasma and its effects on blood platelet behaviour
Imperial Users onl
The use of formal methods for safety-critical systems
An investigation is presented into the use of formal methods for the production of safety-critical systems with embedded software. New theory and procedures are tested on an industrial case study, the formal specification and refinement of a communications protocol for medical devices (the Universal Flexport protocol [copyright]).
On reviewing the current literature, a strong case emerges for grounding any work within an overall perspective that integrates the experience of safety engineering and the correctness of formal methods. Such a basis, it is argued, is necessary for an effective contribution to the delivery with assurance of life-critical software components.
Hence, a safety-oriented framework is proposed which facilitates a natural flow from safety analysis of the entire system through to formal requirements, design, verification and validation for a software model undergoing refinement towards implementation. This framework takes a standard safety lifecycle model and considers where and how formal methods can play apart, resulting in procedures which emphasise the activities most amenable to formal input.
Next, details of the framework are instantiated, based upon the provision of a common formal semantics to represent both the safety analysis and software models. A procedure, FTBuild, is provided for deriving formal requirements as part of the process of generating formalised fault trees. Work is then presented on establishing relations between formalised fault trees and models, extending results of other authors. Also given are some notions of (property) conformance with respect to the given requirements.
The formal approach itself is supported by the enhancement of the theory of con-formance testing that has been developed for communication systems. The basis of this work is the detailed integration of already established theories: a testing system for process algebra (the Experimental System due to Hennessy and de Nicola) and a more general observation framework (developed by the LOTOSphere consortium). Notions of conformance and robustness are then examined in the context of refinement for the process algebra, (Basic) LOTOS, resulting in the adoption of the commonly accepted 'reduction' relation for which a proof is given that it is testable. Then a new algorithm is developed for a single (canonical) tester for reduction, which is unified in that it tests simultaneously for both con-formance and robustness. It also allows, in certain cases, a straightforward implementation as a Full LOTOS process with the ability to give some diagnostics in the case of failure. The text is supported by examples and some guidelines for use.
Finally, having established these foundations, the methodology is demonstrated on the Flexport protocol through two iterations of FTBuild which demonstrate how the activities of specification, safety analysis, validation and refinement are all brought together