3,793 research outputs found

    Education Reform: The Effects of School Consolidation on Teachers and Teaching

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    At least as early as the nineteenth century, the two most related approaches to societal improvement have been restructuring and systemic reform. For education, that has meant school closures as well as consolidation of schools and school districts. Although there exists a substantive literature on educational reform there appears to be little discussion on the impact such actions have on schools. This paper briefly describes research on current issues in rural education with a focus on consolidation. The methodology emphasizes teachers’ knowledge of practice and is followed by the findings, which highlight the impact these reforms have on practicing teachers. The argument is made that government reforms have adopted consolidation of schools and districts as a primary strategy for fiscal accountability. This focus singles out economics, while excluding the cultural and social context embedded within schools and central to the communities in which the schools are situated. In this paper, the argument put forth is that consolidation as a single-minded strategy of education reform is an inadequate framework that places teachers’ work and student learning at risk. The accounts of practicing educators speak for using consolidation only where absolutely necessary and maintaining as many small schools as possible.Depuis au moins le 19e siècle, les deux approches visant l’amélioration de la société les plus liées sont la restructuration et la réforme systémique. Dans le domaine dans l’éducation, cela s’est traduit par la fermeture d’écoles et la consolidation d’écoles et de districts scolaires. Malgré la documentation significative portant sur la réforme éducationnelle, peu de discussion semble exister sur l’impact de telles actions sur les écoles. Cet article décrit brièvement la recherche sur les enjeux actuels en éducation rurale et porte une attention particulière à la consolidation. La méthodologie met l’accent sur les connaissances qu’ont les enseignants de la pratique. Les résultats soulignent l’impact de ces réformes sur les enseignants en exercice. On affirme que les réformes gouvernementales ont adopté la consolidation des écoles et des districts comme stratégie principale pour des raisons de responsabilité financière. Cette concentration sur l’économie exclut le contexte culturel et social qu’on retrouve au sein des écoles et qui est intégré aux communautés dans lesquelles se trouvent ces écoles. Cet article maintient que la consolidation comme stratégie résolue en réforme de l’éducation constitue un cadre inadéquat qui met à risque le travail des enseignants et l’apprentissage par les élèves. Les témoignages des enseignants en exercice militent en faveur de maintenir ouvertes autant de petites écoles que possible et de recourir à la consolidation uniquement lorsque cela est absolument nécessaire.

    Cold atom gravimetry with a Bose-Einstein Condensate

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    We present a cold atom gravimeter operating with a sample of Bose-condensed Rubidium-87 atoms. Using a Mach-Zehnder configuration with the two arms separated by a two-photon Bragg transition, we observe interference fringes with a visibility of 83% at T=3 ms. We exploit large momentum transfer (LMT) beam splitting to increase the enclosed space-time area of the interferometer using higher-order Bragg transitions and Bloch oscillations. We also compare fringes from condensed and thermal sources, and observe a reduced visibility of 58% for the thermal source. We suspect the loss in visibility is caused partly by wavefront aberrations, to which the thermal source is more susceptible due to its larger transverse momentum spread. Finally, we discuss briefly the potential advantages of using a coherent atomic source for LMT, and present a simple mean-field model to demonstrate that with currently available experimental parameters, interaction-induced dephasing will not limit the sensitivity of inertial measurements using freely-falling, coherent atomic sources.Comment: 6 pages, 4 figures. Final version, published PR

    Photonic qubits, qutrits and ququads accurately prepared and delivered on demand

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    Reliable encoding of information in quantum systems is crucial to all approaches to quantum information processing or communication. This applies in particular to photons used in linear optics quantum computing (LOQC), which is scalable provided a deterministic single-photon emission and preparation is available. Here, we show that narrowband photons deterministically emitted from an atom-cavity system fulfill these requirements. Within their 500 ns coherence time, we demonstrate a subdivision into d time bins of various amplitudes and phases, which we use for encoding arbitrary qu-d-its. The latter is done deterministically with a fidelity >95% for qubits, verified using a newly developed time-resolved quantum-homodyne method.Comment: 5 pages, 4 figure

    Optically trapped atom interferometry using the clock transition of large Rb-87 Bose-Einstein condensates

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    We present a Ramsey-type atom interferometer operating with an optically trapped sample of 10^6 Bose-condensed Rb-87 atoms. The optical trap allows us to couple the |F =1, mF =0>\rightarrow |F =2, mF =0> clock states using a single photon 6.8GHz microwave transition, while state selective readout is achieved with absorption imaging. Interference fringes with contrast approaching 100% are observed for short evolution times. We analyse the process of absorption imaging and show that it is possible to observe atom number variance directly, with a signal-to-noise ratio ten times better than the atomic projection noise limit on 10^6 condensate atoms. We discuss the technical and fundamental noise sources that limit our current system, and outline the improvements that can be made. Our results indicate that, with further experimental refinements, it will be possible to produce and measure the output of a sub-shot-noise limited, large atom number BEC-based interferometer. In an addendum to the original paper, we attribute our inability to observe quantum projection noise to the stability of our microwave oscillator and background magnetic field. Numerical simulations of the Gross-Pitaevskii equations for our system show that dephasing due to spatial dynamics driven by interparticle interactions account for much of the observed decay in fringe visibility at long interrogation times. The simulations show good agreement with the experimental data when additional technical decoherence is accounted for, and suggest that the clock states are indeed immiscible. With smaller samples of 5 \times 10^4 atoms, we observe a coherence time of {\tau} = (1.0+0.5-0.3) s.Comment: 22 pages, 6 figures Addendum: 11 pages, 6 figure

    Rheological Droplet Interface Bilayers (rheo-DIBs): Probing the Unstirred Water Layer Effect on Membrane Permeability via Spinning Disk Induced Shear Stress

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    A new rheological droplet interface bilayer (rheo-DIB) device is presented as a tool to apply shear stress on biological lipid membranes. Despite their exciting potential for affecting high-throughput membrane translocation studies, permeability assays conducted using DIBs have neglected the effect of the unstirred water layer (UWL). However as demonstrated in this study, neglecting this phenomenon can cause significant underestimates in membrane permeability measurements which in turn limits their ability to predict key processes such as drug translocation rates across lipid membranes. With the use of the rheo-DIB chip, the effective bilayer permeability can be modulated by applying shear stress to the droplet interfaces, inducing flow parallel to the DIB membranes. By analysing the relation between the effective membrane permeability and the applied stress, both the intrinsic membrane permeability and UWL thickness can be determined for the first time using this model membrane approach, thereby unlocking the potential of DIBs for undertaking diffusion assays. The results are also validated with numerical simulations

    Spallation-Like Phenomenon Induced By Laser Shock Peening Surface Treatment On 7050 Aluminum Alloy

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    Laser shock peening (LSP) is a promising surface treatment for fatigue life extension of metallic materials. The benefits include deeper residual stresses (>1 mm) and a smoother surface finish than conventional glass bead peening. However, fatigue tests on 7050 aluminium alloy specimens have shown that LSP may cause a reduction in life due to internal cracking generated during the process. A series of tests were carried out to identify any technological risks such as internal cracking associated with the use of LSP. Numerical modelling was also carried out and the results of this numerical prediction agreed well with the experimental results

    Detecting new microRNAs in human osteoarthritic chondrocytes identifies miR-3085 as a human, chondrocyte-selective, microRNA

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    Objective: To use deep sequencing to identify novel microRNAs in human osteoarthritic cartilage which have a functional role in chondrocyte phenotype or function. Design: A small RNA library was prepared from human osteoarthritic primary chondrocytes using in-house adaptors and analysed by Illumina sequencing. Novel candidate microRNAs were validated by northern blot and qRT-PCR. Expression was measured in cartilage models. Targets of novel candidates were identified by microarray and computational analysis, validated using 3’-UTR-luciferase reporter plasmids. Protein levels were assessed by western blot and functional analysis by cell adhesion. Results: We identified 990 known microRNAs and 1621 potential novel microRNAs in human osteoarthritic chondrocytes, 60 of the latter were expressed in all samples assayed. MicroRNA-140-3p was the most highly expressed microRNA in osteoarthritic cartilage. Sixteen novel candidate microRNAs were analysed further, of which 6 remained after northern blot analysis. Three novel microRNAs were regulated across models of chondrogenesis, chondrocyte differentiation or cartilage injury. One sequence (novel #11), annotated in rodents as microRNA-3085-3p, was preferentially expressed in cartilage, dependent on chondrocyte differentiation and, in man, is located in an intron of the cartilage-expressed gene CRTAC-1. This microRNA was shown to target the ITGA5 gene directly (which encodes integrin alpha5) and inhibited adhesion to fibronectin (dependent on alpha5beta1 integrin). Conclusion: Deep sequencing has uncovered many potential microRNA candidates expressed in human cartilage. At least three of these show potential functional interest in cartilage homeostasis and osteoarthritis. Particularly, novel #11 (microRNA-3085-3p) which has been identified for the first time in man

    Effects of dalcetrapib in patients with a recent acute coronary syndrome

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    In observational analyses, higher levels of high-density lipoprotein (HDL) cholesterol have been associated with a lower risk of coronary heart disease events. However, whether raising HDL cholesterol levels therapeutically reduces cardiovascular risk remains uncertain. Inhibition of cholesteryl ester transfer protein (CETP) raises HDL cholesterol levels and might therefore improve cardiovascular outcomes
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