2,449 research outputs found

    Looked after children : observations of teacher education students on placement in secondary students

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    This collection of accounts is the work of students of the Professional Graduate Diploma in Education Secondary(PGDE) -a one-year teacher education programme for graduates intending to become teachers in secondary schools. These students were taking an elective module on the education of looked after children. The module was presented on either side of a full-time period of placement in secondary schools during February and March 2008. The placement provided an ideal opportunity for the students to find out more about looked after children from the school perspective. There is a series of 22 accounts representing students' observations while on placement in different schools

    Shear work induced changes in the rheology of model Mozzarella cheeses : a thesis presented in partial fulfilment of the requirements for the degree of Doctor of Philosophy in Food Technology at Massey University, Manawatu, New Zealand

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    Mozzarella cheese is a pasta filata type of cheese. Its manufacture includes a kneading – stretching step that creates a fibrous protein network and distributes fat-serum channels to attain desirable melt functionality on a pizza. During processing and manufacturing of pasta-filata cheese, large deformations take place. For appropriate characterization of a food material, rheological evaluation should be conducted in similar operating conditions, length scales and time scales to those taking place in the actual process. Development of the typical fibrous pasta-filata structure of mozzarella cheese depends on composition and process variables. Critical process variables in the development of cheese structure are time, temperature and shear. In this study we studied the effect of shear work on rheology, structure and melt functionality of model Mozzarella cheese. Three types of model cheeses (full-fat, non-fat and full-fat with added tri-sodium citrate) were prepared by working cheese components together at 70 oC in a twin screw Blentech cooker. Varied amounts of shear work input (2.8-185 kJ/kg) were given to the cheese samples using 50, 150 and 250 rpm screw speeds. Samples were subjected to a range of rheological tests, confocal laser scanning microscopy, fat particle size measurements (DLS) and melt functionality evaluation. While measuring steady shear viscosity of Mozzarella-type cheeses in a rotational rheometer at 70oC, three main difficulties were encountered; wall slip, structural failure during measurement and viscoelastic time dependent effects. A flow curve method was successfully devised to measure steady shear rheology by using serrated plates as surface modification to avoid wall slip, giving enough measurement duration at low shear rate to avoid viscoelastic effects and selecting limited shear steps to cause minimum structural changes. These techniques enabled successful measurement of steady shear viscosity of molten Mozzarella-type cheeses at 70oC at shear rates up to 250 s-1. Strong work thickening was observed for full fat Mozzarella cheese from steady shear rheology, oscillatory rheology, creep, elongational viscosity and tensile testing data. Steady shear rheology and melt functionality were found to be strongly dependent on total shear work input. An exponential increase in consistency coefficient (K from power law model) was observed with increasing amounts of accumulated shear work, indicating work thickening behaviour. An exponential work thickening equation is proposed to describe this behaviour. Excessively worked cheese samples exhibited liquid exudation, poor melting and poor stretch. Nonfat cheese exhibited similar but smaller changes after excessive shear work input. At lower shear work inputs (70 kJ/kg) it behaved like a viscoelastic solid with low frequency dependence. A definite critical point for structural and viscoelastic transition was identified at a medium shear work level (~ 58 kJ/kg at 150 rpm). Similar viscoelastic property changes occurred in non-fat cheese suggesting that major changes were taking place in the protein matrix during working. Confocal microstructures plus macroscopic observations showed systematic changes in structure with increased shear work inputs with unmixed buttery liquid observed at 58 kJ/kg. At very high shear work inputs, > 75 kJ/kg, striations or anisotropy in the microstructures had disappeared and small micro-cracks were evident. Volume-weighted mean fat particle size decreased with shear work input and particle size distributions also changed. To account for the short and long term relaxation response behaviour, a 4-element Burger‘s model was found adequate for fitting the creep data of model cheese at 70 oC but a 6-element model was required at 20 oC. As shear work input increased, retarded compliance decreased and zero shear viscosity increased indicating the more elastic behavior of the cheeses with higher shear work input. Fracture stress and strain for longitudinal samples from elongated full fat cheese did not vary significantly with shear work input up to 26.3 kJ/kg then decreased dramatically at 58.2 kJ/kg. Longitudinal samples with shear work input <30 kJ/kg, demonstrated significant strain hardening. At shear work inputs <30 kJ/kg strong anisotropy was observed in both fracture stress and strain. After a shear work input of 58.2 kJ/kg anisotropy and strain hardening were absent. Perpendicular samples did not show strain hardening at any level of shear work input. A good correlation was found between the steady shear, oscillatory shear and transient rheological properties and the melting properties of the cheeses. The order for the rheological properties in terms of their sensitivity towards both shear work input and melt functionality is ηapp > G‘ > elongational viscosity > consistency coefficient, K. It was concluded that the dominant contributor to the changes in rheology, structure and melt properties with increased shear work was shear induced structural changes to the protein matrix. An increase in calcium induced protein-protein interactions after high shear work at 70 oC. In summary, this thesis provides useful insights to shear work induced changes in material properties. It proposes useful linkages between the manufacturing process and the application of model Mozzarella cheese using appropriate rheological methods. Since the linkages were validated for only one composition and in only one processing environment, it is proposed that they should be tested in other conditions. In order to build a more complete picture, a molecular level study is proposed for future work to elucidate chemical changes during working and find appropriate linkages with physical and functional characteristics

    Discourse Structure in Machine Translation Evaluation

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    In this article, we explore the potential of using sentence-level discourse structure for machine translation evaluation. We first design discourse-aware similarity measures, which use all-subtree kernels to compare discourse parse trees in accordance with the Rhetorical Structure Theory (RST). Then, we show that a simple linear combination with these measures can help improve various existing machine translation evaluation metrics regarding correlation with human judgments both at the segment- and at the system-level. This suggests that discourse information is complementary to the information used by many of the existing evaluation metrics, and thus it could be taken into account when developing richer evaluation metrics, such as the WMT-14 winning combined metric DiscoTKparty. We also provide a detailed analysis of the relevance of various discourse elements and relations from the RST parse trees for machine translation evaluation. In particular we show that: (i) all aspects of the RST tree are relevant, (ii) nuclearity is more useful than relation type, and (iii) the similarity of the translation RST tree to the reference tree is positively correlated with translation quality.Comment: machine translation, machine translation evaluation, discourse analysis. Computational Linguistics, 201

    The Economic Costs and Benefits of Self-Managed Teams Among Skilled Technicians

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    This paper estimates the economic costs and benefits of implementing teams among highly-skilled technicians in a large regional telecommunications company. It matches individual survey and objective performance data for 230 employees in matched pairs of traditionally-supervised and self-managed groups. Multivariate regressions with appropriate controls show that teams do the work of supervisors in 60-70% less time, reducing indirect labor costs by 75 percent per team. Objective measures of quality and labor productivity are unaffected. Team members receive additional overtime pay that represents a 4-5 percent annual wage premium, which may be viewed alternatively as a share in the productivity gains associated with innovation or as a premium for learning skills
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