1,408 research outputs found

    Development of a comprehensive energy model to simulate the energy efficiency of a battery electric vehicle to allow for prototype design optimisation and validation.

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    Masters Degree in mechanical Engineering. University of KwaZulu-Natal, Durban.This dissertation describes the development of an energy model of a battery electric vehicle (BEV) to assist designers in evaluating the impact of overall energy efficiency on vehicle performance. Energy efficiency is a crucial metric for BEVs as it defines the driving range of the vehicle and optimises the limited amount of energy available from the on-board battery pack, typically the most expensive component of the vehicle. Energy modelling also provides other useful information to the designer, such as the range of the vehicle according to legislative drive cycles and the maximum torque required from the motor. An accurate, fast and efficient model is therefore required to simulate BEVs in the early stages of design and for prototype validation. An extensive investigation into BEV modelling and the mechanisms of energy losses within BEVs was conducted. Existing literature was studied to characterise the effect of operating conditions on the efficiency of each mechanism, as well as investigating existing modelling techniques used to simulate each energy loss. A complete vehicle model was built by considering multiple domain modelling methods and the flow of energy between components in both mechanical and electrical domains. Simscapeâ„¢, a MathWorks MATLABâ„¢ tool, was used to build a physics based, forward facing model comprising a combination of custom coded blocks representing the flow of energy from the battery pack to the wheels. The acceleration and speed response of the vehicle was determined over a selected drive cycle, based on vehicle parameters. The model is applicable to normal driving conditions where the power of the motor does not exceed its continuous rating. The model relies on datasheet or non-proprietary parameters. These parameters can be changed depending on the architecture of the BEV and the exact components used, providing model flexibility. The primary model input is a drive cycle and the primary model output is range as well as the dynamic response of other metrics such as battery voltage and motor torque. The energy loss mechanisms are then assessed qualitatively and quantitatively to allow vehicle designers to determine effective strategies to increase the overall energy efficiency of the vehicle. The Mamba BEV, a small, high-power, commercially viable electric vehicle with a 21 kWh lithium-ion battery was simulated using the developed model. As the author was involved in the design and development of the vehicle, required vehicle parameters were easily obtained from manufacturers. The range of the vehicle was determined using the World-Harmonised Light Duty Vehicles Test Procedure and provided an estimated range of 285.3 km for the standard cycle and 420.8 km for the city cycle

    Critical Literacies in Schools : A Primer

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    Readers and writers use a variety of modes of inscription – print, oral and multimedia – to understand, analyze, critique and transform their social, cultural and political worlds. Beginning from Freire (1970), ‘critical literacy’ has become a theoretically diverse educational project, drawing from reader response theory, linguistic and grammatical analysis from critical linguistics, feminist, poststructuralist, postcolonial and critical race theory, and cultural and media studies. In the UK, Australia, Canada, South Africa, New Zealand and the US different approaches to critical literacy have been developed in curriculum and schools. These focus on social and cultural analysis and on how print and digital texts and discourses work, with a necessary and delicate tension between classroom emphasis on student and community cultural ‘voice’ and social analysis – and on explicit engagement with the technical features and social uses of written and multimodal texts

    Molecular architectures of benzoic acid-specific type III polyketide synthases

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    Biphenyl synthase and benzophenone synthase constitute an evolutionarily distinct clade of type III polyketide synthases (PKSs) that use benzoic acid-derived substrates to produce defense metabolites in plants. The use of benzoyl-CoA as an endogenous substrate is unusual for type III PKSs. Moreover, sequence analyses indicate that the residues responsible for the functional diversification of type III PKSs are mutated in benzoic acid-specific type III PKSs. In order to gain a better understanding of structure–function relationships within the type III PKS family, the crystal structures of biphenyl synthase from Malus × domestica and benzophenone synthase from Hypericum androsaemum were compared with the structure of an archetypal type III PKS: chalcone synthase from Malus × domestica. Both biphenyl synthase and benzophenone synthase contain mutations that reshape their active-site cavities to prevent the binding of 4-coumaroyl-CoA and to favor the binding of small hydrophobic substrates. The active-site cavities of biphenyl synthase and benzophenone synthase also contain a novel pocket associated with their chain-elongation and cyclization reactions. Collectively, these results illuminate structural determinants of benzoic acid-specific type III PKSs and expand the understanding of the evolution of specialized metabolic pathways in plants

    Comprehension as social and intellectual practice: Rebuilding curriculum in low socioeconomic and cultural minority schools

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    This article reframes the concept of comprehension as a social and intellectual practice. It reviews current approaches to reading instruction for linguistically and culturally diverse and low socioeconomic students, noting an emphasis on comprehension as autonomous skills. The Four Resources model (Freebody & Luke, 1990) is used to make the case for the integration of comprehension instruction with an emphasis on student cultural and community knowledge, and substantive intellectual and sociocultural content in elementary school curricula. Illustrations are drawn from research underway on the teaching of literacy in primary schools in low SES communities

    Diurnal Preference Predicts Phase Differences in Expression of Human Peripheral Circadian Clock Genes

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    Background: Circadian rhythms play an integral role in human behavior, physiology and health. Individual differences in daily rhythms (chronotypes) can affect individual sleep-wake cycles, activity patterns and behavioral choices. Diurnal preference, the tendency towards morningness or eveningness among individuals, has been associated with interpersonal variation in circadian clock-related output measures, including body temperature, melatonin levels and clock gene mRNA in blood, oral mucosa, and dermal fibroblast cell cultures. Methods: Here we report gene expression data from two principal clock genes sampled from hair follicle cells, a peripheral circadian clock. Hair follicle cells from fourteen individuals of extreme morning or evening chronotype were sampled at three time points. RNA was extracted and quantitative PCR assays were used to measure mRNA expression patterns of two clock genes, 'Per3' and 'Nr1d2'. Results: We found significant differences in clock gene expression over time between chronotype groups, independent of gender or age of participants. Extreme evening chronotypes have a delay in phase of circadian clock gene oscillation relative to extreme morning types. Variation in the molecular clockwork of chronotype groups represents nearly three-hour phase differences ('Per3': 2.61 hours; 'Nr1d2': 3.08 hours, both: 2.86) in circadian oscillations of these clock genes. Conclusions: The measurement of gene expression from hair follicles at three time points allows for a direct, efficient method of estimating phase shifts of a peripheral circadian clock in real-life conditions. The robust phase differences in temporal expression of clock genes associated with diurnal preferences provide the framework for further studies of the molecular mechanisms and gene-by-environment interactions underlying chronotype-specific behavioral phenomena, including social jetlag

    Integrating Integrated Water Management

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    © 2014, Thomas Telford Services Ltd. All rights reserved. The water cycle is a contiguous system interconnected with human activities. Management has tended to be fragmented across anthropocentrically defined disciplines, potentially generating unintended negative consequences. The ecosystem approach and the ecosystem services framework emphasise interlinked, albeit often overlooked, benefits that the natural environment provides for people. This enables recognition and avoidance of potential ‘negative externalities’, identification of solutions optimising benefits across multiple services, and participation of wider constituencies of stakeholders. Systemic, outcome-based approaches are inherently economically efficient, yielding greater cumulative benefits for lower transaction costs by working with natural processes. The ecosystem approach establishes geographical and socio-economic contexts for management ecosystem service outcomes, providing a broader context in which to nest established water resource management methods. The ecosystem approach can also be applied at different scales and to diverse societal activities, internalising into them the value of natural processes. It is amenable to integration into catchment-scale considerations, yet does not present these activities as subsidiary to river basin planning. The addition of ecosystem services for options appraisal in preexisting decision-support tools adapts them to better address multi-benefit goals. Shifts are required in the policy and economic environment, but engineers have an important role in promoting, applying and innovating multibenefit solutions

    Metacognitive beliefs, beliefs about voices and affective symptoms in patients with severe auditory verbal hallucinations

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    Objectives. This study explores associations between metacognitive beliefs and beliefs about voices in patients with severe auditory verbal hallucinations, and their hypothesized relationship with levels of depression and anxiety. Furthermore, it was hypothesized that metacognitive beliefs are better able to explain differences in levels of depression and anxiety, than beliefs about voices. Design. Cross-sectional data were obtained from baseline measurements of a randomized controlled trial. All patients (N = 77) met the criteria for a DSM-IV diagnosis within the schizophrenia spectrum. A correlation analysis was conducted to explore the associations between metacognitive beliefs and beliefs about voices. Regression analysis was performed to test the second hypothesis. Method. Metacognitive beliefs were measured using the MCQ-30. Beliefs about voices were measured using the BAVQ-R. Furthermore, the Beck Depression Inventory-II and the Beck Anxiety Inventory were applied to measure depression and anxiety. All analyses were a priori controlled for gender and level of education. Results. Significant associations were found between negative beliefs about voices and negative metacognitive beliefs. One of the metacognitive beliefs, that is, perceived uncontrollability and danger of thinking, proved to be a key variable in explaining differences in levels of depression and anxiety and seemed to have greater explanatory value than all of the beliefs about voices when analysed simultaneously. Conclusions. The results offer modest support to models emphasizing the fact that metacognitive beliefs are a core feature in the development and maintenance of depression and anxiety in patients with severe auditory verbal hallucinations. © 2012 The British Psychological Society

    The ‘values journey’ of nursing and midwifery students selected using multiple mini interviews; Year One findings

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    Aim: to explore how adult, child and mental health nursing and midwifery students, selected using multiple mini interviews, describe their ‘values journey’ following exposure to the clinical practice environment. Background: Values based recruitment incorporates assessment of healthcare students’ personal values using approaches like multiple mini interviews. Students’ experience of adjustment to their values during their programme is conceptualised as a ‘values journey’. The impact of VBR in alleviating erosion of personal values is unclear. Design A cross-professional longitudinal cohort study was commenced at one university in England in 2016 with data collection points at the end of years one, two and three. Non-probability consecutive sampling resulted in 42 healthcare students (8 adult, 8 child and 9 mental health nursing and 17 midwifery students) taking part. Methods: Six semi-structured focus groups were conducted at the end of participants’ Year One (DC1). Data analysis incorporated inductive and deductive approaches in a hybrid synthesis. Findings: Participants described a ‘values journey’ where their values, particularly communication, courage and wanting to make a difference, were both challenged and retained. Participants personal journeys also acknowledged the: ‘courage it takes to use values’; ‘reality of values in practice’ and ‘need for self-reflection on values’. Conclusion: A ‘values journey’ may begin early in healthcare student’s education programme. This is important to recognise so that appropriate measures are implemented to support students across higher education and clinical practice. Consideration should also be given to the values incorporated in values based recruitment to ensure their fitness for purpose
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