78 research outputs found

    Architectural assessment of mass storage systems at GSFC

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    The topics are presented in viewgraph form and include the following: system functionality; characteristics; data sources; hardware/software systems; and performance assessments

    Detection of static eccentricity fault in PSH induction motor by using external magnetic flux density

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    The objective of this paper is to make a clear and thorough investigation about the effectiveness of Motor Current Signature Analysis (MCSA) for detecting default indexes of static eccentricity in (Principal Slot Harmonics) PSH induction motor. The obtained results using traditional technique (MCSA) are compared with spectrums of external magnetic flux density extracted from healthy and faulty motors. The work is carried out with transient finite element method (FEM) simulations considering motor operation under nominal mechanical load, the notching nature of stator and rotor and the non-linearity behavior of ferromagnetic material are taking into account.Keywords: induction motor; static eccentricity; FEM, PSH; MCSA; magnetic flux densit

    Connecting observations of student and teacher learning: an examination of dialogic processes in Lesson Study discussions in mathematics

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    Lesson Study is rapidly becoming one of the most adopted models of teacher professional development worldwide. In this paper, we examine the teachers’ discussions that are an integral part of the Lesson Study research cycle. In particular, we investigate the ‘dialogic mechanisms’ that enable teachers’ pedagogical intentions to be developed within the context of discussions that stem from observations of students as they address mathematical problems. In so doing we hypothesize about the nature of the ‘dialogic space’ that is created and how this allows teachers to move from the collaborative analysis of student outcomes to an enhanced understanding of pedagogical intentions in mathematics. Data for this paper derive from a large research project taking place in Camden, London. This project aims to implement Lesson Study in the context of the introduction of a New National Curriculum for Mathematics in England. It involves a large cohort of mathematics teachers across primary and secondary schools. Quantitative analysis of video-recorded Lesson Study discussions is reviewed and one illustrative case study is included to contextualise the quantitative data. Findings suggest that a focus on student outcomes enables teachers to collaborate effectively on developing pedagogical intentions to directly address student need. Further, it seems that particular features of dialogue are evident where teachers move to an agreed perspective on pedagogic change; and evidence of ‘supportive moves’ in interactions suggest that a form of dialogic space is necessary if all teachers in a Lesson Study group are to learn from shared understandings about future teaching and learning needs.The research was funded from the Office of the Lord Mayor of London

    Teacher learning in the context of Lesson Study: A video-based analysis of teacher discussions

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    This paper contributes to our understanding of teacher learning in the context of Lesson Study (LS), a model of professional development that involves collaborative lesson planning and evaluation. Video-recorded LS discussions of mathematics teachers based in London were analysed for this purpose. Two inter-related studies are presented: the first involved the construction of a reliable coding protocol for video analysis; the second used this protocol for coding 120 fragments of discussions amongst 91 teachers. Findings are discussed with reference to tests of reliability and results of multilevel analysis, which reveal differential effects of particular forms of interactions on learning processes.This research was made possible through a grant of the London School Excellence Fund

    The impact of Lesson Study professional development on the quality of teacher learning

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    This paper aims to increase our understanding of the impact of Lesson Study (LS) on the quality of teacher learning. It draws on longitudinal and cross-sectional data from three waves of data collection from 214 teachers engaged in LS during one full school year. The findings showed positive effects of Lesson Study on meaning-oriented and application-oriented teacher learning and a negative effect on problematic learning. Less experienced teachers showed the highest gain in meaning-oriented learning. The paper contributes to advancement of our theoretical understanding of teacher learning as it provides evidence of mechanisms through which professional development impacts teacher learning

    Technology Assessment of High Capacity Data Storage Systems: Can We Avoid a Data Survivability Crisis?

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    This technology assessment of long-term high capacity data storage systems identifies an emerging crisis of severe proportions related to preserving important historical data in science, healthcare, manufacturing, finance and other fields. For the last 50 years, the information revolution, which has engulfed all major institutions of modem society, centered itself on data-their collection, storage, retrieval, transmission, analysis and presentation. The transformation of long term historical data records into information concepts, according to Drucker, is the next stage in this revolution towards building the new information based scientific and business foundations. For this to occur, data survivability, reliability and evolvability of long term storage media and systems pose formidable technological challenges. Unlike the Y2K problem, where the clock is ticking and a crisis is set to go off at a specific time, large capacity data storage repositories face a crisis similar to the social security system in that the seriousness of the problem emerges after a decade or two. The essence of the storage crisis is as follows: since it could take a decade to migrate a peta-byte of data to a new media for preservation, and the life expectancy of the storage media itself is only a decade, then it may not be possible to complete the transfer before an irrecoverable data loss occurs. Over the last two decades, a number of anecdotal crises have occurred where vital scientific and business data were lost or would have been lost if not for major expenditures of resources and funds to save this data, much like what is happening today to solve the Y2K problem. A pr-ime example was the joint NASA/NSF/NOAA effort to rescue eight years worth of TOVS/AVHRR data from an obsolete system, which otherwise would have not resulted in the valuable 20-year long satellite record of global warming. Current storage systems solutions to long-term data survivability rest on scalable architectures having parallel paths for data migration

    Reporting errors, incidence and risk factors for postpartum haemorrhage and progression to severe PPH:a prospective observational study

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    OBJECTIVE: To quantify reporting errors, measure incidence of postpartum haemorrhage (PPH) and define risk factors for PPH (≥500 ml) and progression to severe PPH (≥1500 ml). DESIGN: Prospective observational study. SETTING: Two UK maternity services. POPULATION: Women giving birth between 1 August 2008 and 31 July 2009 (n = 10 213). METHODS: Weighted sampling with sequential adjustment by multivariate analysis. MAIN OUTCOME MEASURES: Incidence and risk factors for PPH and progression to severe PPH. RESULTS: Errors in transcribing blood volume were frequent (14%) with evidence of threshold preference and avoidance. The incidences of PPH ≥500, ≥1500 and ≥2500 ml were 33.7% (95% CI 31.2–36.2), 3.9% (95% CI 3.3–4.6) and 0.8% (95% CI 0.6–1.0). New independent risk factors predicting PPH ≥ 500 ml included Black African ethnicity (adjusted odds ratio [aOR] 1.77, 95% CI 1.31–2.39) and assisted conception (aOR 2.93, 95% CI 1.30–6.59). Modelling demonstrated how prepregnancy- and pregnancy-acquired factors may be mediated through intrapartum events, including caesarean section, elective (aOR 24.4, 95% CI 5.53–108.00) or emergency (aOR 40.5, 95% CI 16.30–101.00), and retained placenta (aOR 21.3, 95% CI 8.31–54.7). New risk factors were identified for progression to severe PPH, including index of multiple deprivation (education, skills and training) (aOR 1.75, 95% CI 1.11–2.74), multiparity without caesarean section (aOR 1.65, 95% CI 1.20–2.28) and administration of steroids for fetal reasons (aOR 2.00, 95% CI 1.24–3.22). CONCLUSIONS: Sequential, interacting, traditional and new risk factors explain the highest rates of PPH and severe PPH reported to date

    Removal of Escherichia coli and Faecal Coliforms from Surface Water and Groundwater by Household Water Treatment Devices/Systems: A Sustainable Solution for Improving Water Quality in Rural Communities of the Southern African Development Community Region

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    There is significant evidence that household water treatment devices/systems (HWTS) are capable of dramatically improving microbially contaminated water quality. The purpose of this study was to examine five filters [(biosand filter-standard (BSF-S); biosand filter-zeolite (BSF-Z); bucket filter (BF); ceramic candle filter (CCF); and silver-impregnated porous pot (SIPP)] and evaluate their ability to improve the quality of drinking water at the household level. These HWTS were manufactured in the workshop of the Tshwane University of Technology and evaluated for efficiency to remove turbidity, faecal coliforms and Escherichia coli from multiple water source samples, using standard methods. The flow rates ranged from 0.05 L/h to 2.49 L/h for SIPP, 1 L/h to 4 L/h for CCF, 0.81 L/h to 6.84 L/h for BSF-S, 1.74 L/h to 19.2 L/h and 106.5 L/h to 160.5 L/h for BF The turbidity of the raw water samples ranged between 2.17 and 40.4 NTU. The average turbidity obtained after filtration ranged from 0.6 to 8 NTU (BSF-S), 1 to 4 NTU (BSF-Z), 2 to 11 NTU (BF), and from 0.6 to 7 NTU (CCF) and 0.7 to 1 NTU for SIPP. The BSF-S, BSF-Z and CCF removed 2 to 4 log10 (99% to 100%) of coliform bacteria, while the BF removed 1 to 3 log (90% to 99.9%) of these bacteria. The performance of the SIPP in removing turbidity and indicator bacteria (>5 log10, 100%) was significantly higher compared to that of the other HWTS (p < 0.05). The findings of this study indicate that the SIPP can be an effective and sustainable HWTS for the Southern African Development Community (SADC) rural communities, as it removed the total concentration of bacteria from test water, can be manufactured using locally available materials, and is easy to operate and to maintain

    Identification of Adropin as a Secreted Factor Linking Dietary Macronutrient Intake with Energy Homeostasis and Lipid Metabolism

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    Obesity and nutrient homeostasis are linked by mechanisms that are not fully elucidated. Here we describe a secreted protein, adropin, encoded by a gene, Energy Homeostasis Associated (Enho), expressed in liver and brain. Liver Enho expression is regulated by nutrition: lean C57BL/6J mice fed high-fat diet (HFD) exhibited a rapid increase, while fasting reduced expression compared to controls. However, liver Enho expression declines with diet-induced obesity (DIO) associated with 3 months of HFD or with genetically induced obesity, suggesting an association with metabolic disorders in the obese state. In DIO mice, transgenic overexpression or systemic adropin treatment attenuated hepatosteatosis and insulin resistance independently of effects on adiposity or food intake. Adropin regulated expression of hepatic lipogenic genes and adipose tissue peroxisome proliferator-activated receptor gamma, a major regulator of lipogenesis. Adropin may therefore be a factor governing glucose and lipid homeostasis, which protects against hepatosteatosis and hyperinsulinemia associated with obesity. © 2008 Elsevier Inc. All rights reserved
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