5,223 research outputs found

    Educational effectiveness and improvement in developing societies. Some experiences from the Primary Education Quality Improvement Project in Indonesia

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    The improvement of education in developing societies might benefit from theory and research on educational effectiveness. ... The research evidence points at the importance of factors at the classroom level and the relatively small possibilities that the school and the above school level have to influence those factors at the classroom level. This is illustrated by the evaluation of the primary education quality improvement project in Indonesia, a project that aimed at the improvement of education through teacher professional development, provision of textbooks, community participation and management of schools. The results tend to support the general feeling about educational effectiveness. Conclusions stress the importance of the development of knowledge by (inter)national consultants, the content of the intervention - educational effectiveness and improvement and the adaptation of the knowledge to national and local circumstances - and procedural and technical knowledge how to design, implement and evaluate educational interventions. (DIPF/orig.

    Influence of temporal structure of the sonic environment on annoyance

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    On protecting farmers' new varieties: new approaches to rights on collective innovations in plant genetic resources

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    "Current farmers' breeding goes beyond the gradual selection in landraces, and includes development and maintenance of major new farmers' varieties that are rather uniform, in particular in South-East Asia. Modern varieties developed in the formal sector have simply replaced landraces as the source of diversity, but have not abolished farmers' breeding practices. Interpretations of the new international agreements on plant genetic resources should protect the development of modern farmers' varieties. However, ensuring recognition of collective innovation, allowing access to relevant germplasm sources for farmers' breeding activities, keeping materials freely available, and arranging for effective benefit sharing, all form major challenges. This paper proposes a new protective measure: namely “origin recognition rights." Author's AbstractLandraces, Farmers' varieties, Collective rights, Declaration of origin, Origin recognition, Germplasm resources,

    Ground State of the Easy-Axis Rare-Earth Kagom\'e Langasite Pr3_3Ga5_5SiO14_{14}

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    We report muon spin relaxation (μ\muSR) and 69,71^{69,71}Ga nuclear quadrupolar resonance (NQR) local-probe investigations of the kagom\'e compound Pr3_3Ga5_5SiO14_{14}. Small quasi-static random internal fields develop below 40 K and persist down to our base temperature of 21 mK. They originate from hyperfine-enhanced 141^{141}Pr nuclear magnetism which requires a non-magnetic Pr3+^{3+} crystal-field (CF) ground state. Besides, we observe a broad maximum of the relaxation rate at 10\simeq 10 K which we attribute to the population of the first excited magnetic CF level. Our results yield a Van-Vleck paramagnet picture, at variance with the formerly proposed spin-liquid ground state.Comment: minor change

    Spin Anisotropy and Slow Dynamics in Spin Glasses

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    We report on an extensive study of the influence of spin anisotropy on spin glass aging dynamics. New temperature cycle experiments allow us to compare quantitatively the memory effect in four Heisenberg spin glasses with various degrees of random anisotropy and one Ising spin glass. The sharpness of the memory effect appears to decrease continuously with the spin anisotropy. Besides, the spin glass coherence length is determined by magnetic field change experiments for the first time in the Ising sample. For three representative samples, from Heisenberg to Ising spin glasses, we can consistently account for both sets of experiments (temperature cycle and magnetic field change) using a single expression for the growth of the coherence length with time.Comment: 4 pages and 4 figures - Service de Physique de l'Etat Condense CNRS URA 2464), DSM/DRECAM, CEA Saclay, Franc

    Quantum Kagome antiferromagnet ZnCu3(OH)6Cl2

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    The frustration of antiferromagnetic interactions on the loosely connected kagome lattice associated to the enhancement of quantum fluctuations for S=1/2 spins was acknowledged long ago as a keypoint to stabilize novel ground states of magnetic matter. Only very recently, the model compound Herbersmithite, ZnCu3(OH)6Cl2, a structurally perfect kagome antiferromagnet, could be synthesized and enables a close comparison to theories. We review and classify various experimental results obtained over the past years and underline some of the pending issues.Comment: 23 pages, 16 figures, invited paper in J. Phys. Soc. Jpn, special topics issue on "Novel States of Matter Induced by Frustration", to be published in Jan. 201

    Apex Peptide Elution Chain Selection: A New Strategy for Selecting Precursors in 2D-LC-MALDI-TOF/TOF Experiments on Complex Biological Samples

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    LC-MALDI provides an often overlooked opportunity to exploit the separation between LC-MS and MS/MS stages of a 2D-LC-MS-based proteomics experiment, that is, by making a smarter selection for precursor fragmentation. Apex Peptide Elution Chain Selection (APECS) is a simple and powerful method for intensity-based peptide selection in a complex sample separated by 2D-LC, using a MALDI-TOF/TOF instrument. It removes the peptide redundancy present in the adjacent first-dimension (typically strong cation exchange, SCX) fractions by constructing peptide elution profiles that link the precursor ions of the same peptide across SCX fractions. Subsequently, the precursor ion most likely to fragment successfully in a given profile is selected for fragmentation analysis, selecting on precursor intensity and absence of adjacent ions that may cofragment. To make the method independent of experiment-specific tolerance criteria, we introduce the concept of the branching factor, which measures the likelihood of false clustering of precursor ions based on past experiments. By validation with a complex proteome sample of Arabidopsis thaliana, APECS identified an equivalent number of peptides as a conventional data-dependent acquisition method but with a 35% smaller work load. Consequently, reduced sample depletion allowed further selection of lower signal-to-noise ratio precursor ions, leading to a larger number of identified unique peptides.

    Vesignieite BaCu3V2O8(OH)2 as a Candidate Spin-1/2 Kagome Antiferromagnet

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    A polycrystalline sample of vesignieite BaCu3V2O8(OH)2 comprising a nearly ideal kagome lattice composed of Cu2+ ions carrying spin 1/2 has been synthesized and studied by magnetization and heat capacity measurements. Magnetic susceptibility shows a neither long range order, a spin glass transition nor a spin gap down to 2 K, in spite of a moderately strong antiferromagnetic interaction of J/kB = 53 K between nearest-neighbor spins. A broad peak observed at a temperature corresponding to 0.4J in intrinsic magnetic susceptibility indicates a marked development of the short-range order. The ground state of vesignieite is probably a gapless spin liquid or is accompanied by a very small gap less than J/30.Comment: 4 pages, 5 figure
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