3,390 research outputs found

    EFFECTS OF UNMODELED LATENT CLASSES ON MULTILEVEL GROWTH MIXTURE ESTIMATION IN VALUE-ADDED MODELING

    Get PDF
    Fairness is necessary to successful evaluation, whether the context is simple and concrete or complex and abstract. Fair evaluation must begin with careful data collection, with clear operationalization of variables whose relationship(s) will represent the outcome(s) of interest. In particular, articulating what it is in the data that needs to be modeled, as well as the relationships of interest, must be specified before conducting any research; these two features will inform both study design and data collection. Heterogeneity is a key characteristic of data that can complicate the data collection design, and especially analysis and interpretation, interfering with or influencing the perception of the relationship(s) that the data will be used to investigate or evaluate. However, planning for, and planning to account for, heterogeneities in data are also critical to the research process, to support valid interpretation of results from any statistical analysis. The multilevel growth mixture model is a new analytic method specifically developed to accommodate heterogeneity so as to minimize the effect of variability on precision in estimation and to reduce bias that may arise in hierarchical data. This is particularly important in the Value Added Model context - where decisions and evaluations about teaching effectiveness are made, because estimates could be contaminated, biased, or simply less precise when data are modeled inappropriately. This research will investigate the effects of un-accounted for heterogeneity at level 1 on the precision of level-2 estimates in multilevel data utilizing the multilevel growth mixture model and multilevel linear growth model

    Impurity Effects on Quantum Depinning of Commensurate Charge Density Waves

    Full text link
    We investigate quantum depinning of the one-dimensional (1D) commensurate charge-density wave (CDW) in the presence of one impurity theoretically. Quantum tunneling rate below but close to the threshold field is calculated at absolute zero temperature by use of the phase Hamiltonian within the WKB approximation. We show that the impurity can induce localized fluctuation and enhance the quantum depinning. The electric field dependence of the tunneling rate in the presence of the impurity is different from that in its absence.Comment: 14 pages with 13 figures. Submitted to J. Phys. Soc. Jp

    New conjecture on exact Dirac zeromodes of lattice fermions

    Full text link
    We propose a new conjecture on the relation between the species doubling of lattice fermions and the topology of manifold on which the fermion action is defined. Our conjecture claims that the maximal number of fermion species on a finite-volume and finite-spacing lattice defined by discretizing a DD-dimensional manifold is equal to the summation of the Betti numbers of the manifold. We start with reconsidering species doubling of naive fermions on the lattices whose topologies are torus (TDT^{D}), hyperball (BDB^D) and their direct-product space (TD×BdT^{D} \times B^{d}). We find that the maximal number of species is in exact agreement with the sum of Betti numbers r=0Dβr\sum^{D}_{r=0} \beta_{r} for these manifolds. Indeed, the 4D4D lattice fermion on torus has up to 1616 species while the sum of Betti numbers of T4T^4 is 1616. This coincidence holds also for the DD-dimensional hyperball and their direct-product space TD×BdT^{D} \times B^{d}. We study several examples of lattice fermions defined on discretized hypersphere (SDS^{D}), and find that it has up to 22 species, which is the same number as the sum of Betti numbers of SDS^{D}. From these facts, we conjecture the equivalence of the maximal number of fermion species and the summation of Betti numbers. We discuss a program for proof of the conjecture in terms of Hodge theory and spectral graph theory.Comment: 31 pages, 16 figure

    Concurrent statistical learning of ignored and attended sound sequences: An MEG study

    Get PDF
    In an auditory environment, humans are frequently exposed to overlapping sound sequences such as those made by human voices and musical instruments, and we can acquire information embedded in these sequences via attentional and nonattentional accesses. Whether the knowledge acquired by attentional accesses interacts with that acquired by nonattentional accesses is unknown, however. The present study examined how the statistical learning of two overlapping sound sequences is reflected in neurophysiological and behavioural responses, and how the learning effects are modulated by attention to each sequence. Statistical learning in this experimental paradigm was reflected in a neuromagnetic response predominantly in the right hemisphere, and the learning effects were not retained when attention to the tone streams was switched during the learning session. These results suggest that attentional and nonattentional learning scarcely interact with each other, and that there may be a specific system for nonattentional learning, which is independent of attentional learning

    Study of Sun-Earth Couplings using MAGDAS/CPMN Data

    Get PDF
    第2回極域科学シンポジウム/第35回極域宙空圏シンポジウム 11月15日(火) 国立極地研究所 2階大会議

    Characterization of Catalase from Psychrotolerant Psychrobacter piscatorii T-3 Exhibiting High Catalase Activity

    Get PDF
    A psychrotolerant bacterium, strain T-3 (identified as Psychrobacter piscatorii), that exhibited an extraordinarily high catalase activity was isolated from the drain pool of a plant that uses H2O2 as a bleaching agent. Its cell extract exhibited a catalase activity (19,700 U·mg protein−1) that was higher than that of Micrococcus luteus used for industrial catalase production. Catalase was approximately 10% of the total proteins in the cell extract of the strain. The catalase (PktA) was purified homogeneously by only two purification steps, anion exchange and hydrophobic chromatographies. The purified catalase exhibited higher catalytic efficiency and higher sensitivity of activity at high temperatures than M. luteus catalase. The deduced amino acid sequence showed the highest homology with catalase of Psycrobacter cryohalolentis, a psychrotolelant bacterium obtained from Siberian permafrost. These findings suggest that the characteristics of the PktA molecule reflected the taxonomic relationship of the isolate as well as the environmental conditions (low temperatures and high concentrations of H2O2) under which the bacterium survives. Strain T-3 efficiently produces a catalase (PktA) at a higher rate than Exiguobacterium oxidotolerans, which produces a very strong activity of catalase (EktA) at a moderate rate, in order to adapt to high concentration of H2O2
    corecore