604 research outputs found

    Perceptions of gifted education in middle school and the role of principal

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    The purpose of this study is to determine the extent to which middle school principals are encouraging particular research-based practices relevant to teaching students with high ability in their buildings. In addition, the study will examine principals\u27 and teachers\u27 perceptions of principal practices related to the improvement in the achievement of gifted students in middle school; The study\u27s design will utilize a mixed method using surveys and interviews. Quantitative methodology will be employed to gain and understanding of the perceptions of principals and teachers through the utilization of the survey. The study will also employ qualitative methodology by interviewing a group of principals and teachers. The population for this study will be all Nevada public middle school (grade 6-8) principals. These participants will be both men and women who are employed as principals in a Nevada public middle school. The population will consist of 129 principals. These middle schools are located in rural, suburban, and urban areas of the state; The study supported the conclusion that, in general, principals are knowledgeable of research-based instructional practices relative to teaching students with high ability. However, teachers do not support the perception of principals that they are encouraging the use of these practices in the classrooms of their buildings. Furthermore, the findings of this study suggest discrepancies between principals\u27 perceived knowledge about research-based instructional practices geared towards students with high ability and their actual pedagogical knowledge

    Ultraslow Electron Spin Dynamics in GaAs Quantum Wells Probed by Optically Pumped NMR

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    Optically pumped nuclear magnetic resonance (OPNMR) measurements were performed in two different electron-doped multiple quantum well samples near the fractional quantum Hall effect ground state nu=1/3. Below 0.5K, the spectra provide evidence that spin-reversed charged excitations of the nu=1/3 ground state are localized over the NMR time scale of ~40 microseconds. Furthermore, by varying NMR pulse parameters, the electron spin temperature (as measured by the Knight shift) could be driven above the lattice temperature, which shows that the value of the electron spin-lattice relaxation time lies between 100 microseconds and 500 milliseconds at nu=1/3.Comment: 6 pages (REVTEX), 6 eps figures embedded in text; published version; minor changes to match published versio

    History, Policy and Nursing Practice Implications of the Plan B® Emergency Contraceptive

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    Numerous policy changes have expanded access to emergency contraception, such as Plan B®, in recent years. Plan B® is a progesterone‐based medication that prevents pregnancy from occurring up to 120 hours after unprotected intercourse by preventing ovulation and tubal transport. Increased access to Plan B® allows women to make independent decisions regarding reproductive health. Nurses play an important role in providing education as well as comprehensive, compassionate and holistic care.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/111254/1/life12186.pd

    Self-consistent propagation of flux ropes in realistic coronal simulations

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    The aim of this paper is to demonstrate the possible use of the new coronal model COCONUT to compute a detailed representation of a numerical CME at 0.1~AU, after its injection at the solar surface and propagation in a realistic solar wind, as derived from observed magnetograms. We present the implementation and propagation of modified Titov-D\'emoulin (TDm) flux ropes in the COCONUT 3D MHD coronal model. The background solar wind is reconstructed in order to model two opposite configurations representing a solar activity maximum and minimum respectively. Both were derived from magnetograms which were obtained by the Helioseismic and Magnetic Imager (HMI) onboard the Solar Dynamic Observatory (SDO) satellite. We track the propagation of 24 flux ropes, which differ only by their initial magnetic flux. We especially investigate the geometry of the flux rope during the early stages of the propagation as well as the influence of its initial parameters and solar wind configuration on 1D profiles derived at 0.1~AU. At the beginning of the propagation, the shape of the flux ropes varies between simulations during low and high solar activity. We find dynamics that are consistent with the standard CME model, such as the pinching of the legs and the appearance of post-flare loops. Despite the differences in geometry, the synthetic density and magnetic field time profiles at 0.1~AU are very similar in both solar wind configurations. These profiles are similar to those observed further in the heliosphere and suggest the presence of a magnetic ejecta composed of the initially implemented flux rope and a sheath ahead of it. Finally, we uncover relationships between the properties of the magnetic ejecta, such as density or speed and the initial magnetic flux of our flux ropes.Comment: 20 pages, 13 figure

    Normalization of drug and therapeutic concepts with Thera-Py

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    OBJECTIVE: The diversity of nomenclature and naming strategies makes therapeutic terminology difficult to manage and harmonize. As the number and complexity of available therapeutic ontologies continues to increase, the need for harmonized cross-resource mappings is becoming increasingly apparent. This study creates harmonized concept mappings that enable the linking together of like-concepts despite source-dependent differences in data structure or semantic representation. MATERIALS AND METHODS: For this study, we created Thera-Py, a Python package and web API that constructs searchable concepts for drugs and therapeutic terminologies using 9 public resources and thesauri. By using a directed graph approach, Thera-Py captures commonly used aliases, trade names, annotations, and associations for any given therapeutic and combines them under a single concept record. RESULTS: We highlight the creation of 16 069 unique merged therapeutic concepts from 9 distinct sources using Thera-Py and observe an increase in overlap of therapeutic concepts in 2 or more knowledge bases after harmonization using Thera-Py (9.8%-41.8%). CONCLUSION: We observe that Thera-Py tends to normalize therapeutic concepts to their underlying active ingredients (excluding nondrug therapeutics, eg, radiation therapy, biologics), and unifies all available descriptors regardless of ontological origin

    Spectroscopic Evidence for the Localization of Skyrmions near Nu=1 as T->0

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    Optically pumped nuclear magnetic resonance measurements of Ga-71 spectra were carried out in an n-doped GaAs/Al0.1Ga0.9As multiple quantum well sample near the integer quantum Hall ground state Nu=1. As the temperature is lowered (down to T~0.3 K), a ``tilted plateau'' emerges in the Knight shift data, which is a novel experimental signature of quasiparticle localization. The dependence of the spectra on both T and Nu suggests that the localization is a collective process. The frozen limit spectra appear to rule out a 2D lattice of conventional skyrmions.Comment: 4 pages (REVTEX), 5 eps figures embedded in text, published versio

    Fast Matrix Multiplication via Compiler-only Layered Data Reorganization and Intrinsic Lowering

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    The resurgence of machine learning has increased the demand for high-performance basic linear algebra subroutines (BLAS), which have long depended on libraries to achieve peak performance on commodity hardware. High-performance BLAS implementations rely on a layered approach that consists of tiling and packing layers, for data (re)organization, and micro kernels that perform the actual computations. The creation of high-performance micro kernels requires significant development effort to write tailored assembly code for each architecture. This hand optimization task is complicated by the recent introduction of matrix engines by IBM's POWER10 MMA, Intel AMX, and Arm ME to deliver high-performance matrix operations. This paper presents a compiler-only alternative to the use of high-performance libraries by incorporating, to the best of our knowledge and for the first time, the automatic generation of the layered approach into LLVM, a production compiler. Modular design of the algorithm, such as the use of LLVM's matrix-multiply intrinsic for a clear interface between the tiling and packing layers and the micro kernel, makes it easy to retarget the code generation to multiple accelerators. The use of intrinsics enables a comprehensive performance study. In processors without hardware matrix engines, the tiling and packing delivers performance up to 22x (Intel), for small matrices, and more than 6x (POWER9), for large matrices, faster than PLuTo, a widely used polyhedral optimizer. The performance also approaches high-performance libraries and is only 34% slower than OpenBLAS and on-par with Eigen for large matrices. With MMA in POWER10 this solution is, for large matrices, over 2.6x faster than the vector-extension solution, matches Eigen performance, and achieves up to 96% of BLAS peak performance

    Observation of a new phase transition between fully and partially polarized quantum Hall states with charge and spin gaps at ν=2/3\nu = 2/3

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    The average electron spin-polarization P\cal P of two-dimensional electron gas confined in GaAs/GaAlAs\rm GaAs/GaAlAs multiple quantum-wells was measured by nuclear magnetic resonance (NMR) near the fractional quantum Hall state with filling factor ν=2/3\nu={2/3}. Above this filling factor (2/3ν<0.85{{2/3}} \leq \nu < 0.85), a strong depolarization is observed corresponding to two spin flips per additional flux quantum. The most remarkable behavior of the polarization is observed at ν=2/3\nu ={{2/3}}, where a quantum phase transition from a partially polarized (P3/4{\cal P} \approx {{3/4}}) to a fully polarized (P=1{\cal P} = 1) state can be driven by increasing the ratio between the Zeeman and the Coulomb energy above a critical value ηc=ΔZΔC=0.0185\eta_{c} = \frac{\Delta_{Z}}{\Delta_{C}} = 0.0185.Comment: 4 pages including 4 figure

    NMR Determination of 2D Electron Spin Polarization at ν=1/2\nu=1/2

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    Using a `standard' NMR spin-echo technique we determined the spin polarization of two-dimensional electrons, confined to GaAs quantum wells, from the hyperfine shift of Ga nuclei in the wells. Concentrating on the temperature and magnetic field dependencies of spin polarization at Landau level filling factor ν=1/2\nu =1/2, we find that the results are described well by a simple model of non-interacting composite fermions, although some inconsistencies remain when the two-dimensional electron system is tilted in the magnetic field.Comment: 4 pages (REVTEX) AND 4 figures (PS

    Tunneling into Ferromagnetic Quantum Hall States: Observation of a Spin Bottleneck

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    We explore the characteristics of equilibrium tunneling of electrons from a 3D electrode into a high mobility 2D electron system. For most 2D Landau level filling factors, we find that tunneling can be characterized by a single, well-defined tunneling rate. However, for spin-polarized quantum Hall states (nu = 1, 3 and 1/3) tunneling occurs at two distinct rates that differ by up to 2 orders of magnitude. The dependence of the two rates on temperature and tunnel barrier thickness suggests that slow in-plane spin relaxation creates a bottleneck for tunneling of electrons.Comment: 5 pages, 4 figures, submitted to PR
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