21,732 research outputs found

    Quality Indicators Guiding Secondary Career and Technical Education Programs of Study

    Full text link
    The purpose of this study was to examine quality indicators currently guiding the rigor of secondary career and technical education (CTE) programs of study in the United States. Quality indicators are desirable characteristics or expectations for a comprehensive and effective CTE program of study. As of May 2017, we were able to locate publicly accessible secondary CTE quality program standards/guidelines for 38 states. A majority (n=24) updated their secondary CTE quality program standards/guidelines within the last five years (i.e., 2012-2017). Deductive content analysis was conducted to examine the 38 state profiles using the Association of Career and Technical Education (ACTE) Quality CTE Program of Study Framework 4.0 for coding purposes. Common quality elements and key quality indicators were identified from those state documents, which supplements the ACTE Framework. Implications and examples for practice are also discussed

    On Evolution of the Pair-Electromagnetic Pulse of a Charge Black Hole

    Full text link
    Using hydrodynamic computer codes, we study the possible patterns of relativistic expansion of an enormous pair-electromagnetic-pulse (P.E.M. pulse); a hot, high density plasma composed of photons, electron-positron pairs and baryons deposited near a charged black hole (EMBH). On the bases of baryon-loading and energy conservation, we study the bulk Lorentz factor of expansion of the P.E.M. pulse by both numerical and analytical methods.Comment: A&A macros, 2 pages, 1 figure and postscrit file. To appear in A&A Suppl. Series, Proceeding of Rome98 GRB workshop, ed. L. Pira and F. Fronter

    Quantum computing through electron propagation in the edge states of quantum spin Hall systems

    Full text link
    We propose to implement quantum computing based on electronic spin qubits by controlling the propagation of the electron wave packets through the helical edge states of quantum spin Hall systems (QSHs). Specfically, two non-commutative single-qubit gates, which rotate a qubit around z and y axes, can be realized by utilizing gate voltages either on a single QSH edge channel or on a quantum point contact structure. The more challenging two-qubit controlled phase gate can be implemented through the on-demand capacitive Coulomb interaction between two adjacent edge channels from two parallel QSHs. As a result, a universal set of quantum gates can be achieved in an all-electrical way. The fidelity and purity of the two-qubit gate are calculated with both time delay and finite width of the wave packets taken into consideration, which can reach high values with the existing high-quality single electron source

    Strong electric fields induced on a sharp stellar boundary

    Full text link
    Due to a first order phase transition, a compact star may have a discontinuous distribution of baryon as well as electric charge densities, as e.g. at the surface of a strange quark star. The induced separation of positive and negative charges may lead to generation of supercritical electric fields in the vicinity of such a discontinuity. We study this effect within a relativistic Thomas-Fermi approximation and demonstrate that the strength of the electric field depends strongly on the degree of sharpness of the surface. The influence of strong electric fields on the stability of compact stars is discussed. It is demonstrated that stable configurations appear only when the counter-pressure of degenerate fermions is taken into consideration.Comment: 13 pages, 2 figure

    Hofstadter-type energy spectra in lateral superlattices defined by periodic magnetic and electrostatic fields

    Full text link
    We calculate the energy spectrum of an electron moving in a two-dimensional lattice which is defined by an electric potential and an applied perpendicular magnetic field modulated by a periodic surface magnetization. The spatial direction of this magnetization introduces complex phases into the Fourier coefficients of the magnetic field. We investigate the effect of the relative phases between electric and magnetic modulation on band width and internal structure of the Landau levels.Comment: 5 LaTeX pages with one gif figure to appear in Phys. Rev.

    Why is a noble metal catalytically active? The role of the O-Ag interaction in the function of silver as an oxidation catalyst

    Get PDF
    Extensive density-functional theory calculations, and taking into account temperature and pressure, affords a comprehensive picture of the behavior and interaction of oxygen and Ag(111), and provides valuable insight into the function of silver as an oxidation catalyst. The obtained phase-diagram reveals the most stable species present in a given environment and thus identifies (and excludes) possibly active oxygen species. In particular, for the conditions of ethylene epoxidation, a thin oxide-like structure is most stable, suggesting that such atomic O species are actuating the catalysis, in contrast to hitherto proposed molecular-like species.Comment: 4 pages including 3 figures, Related publications can be found at http://www.fhi-berlin.mpg.de/th/paper.htm

    Study of BcB_{c}^{-} {\to} J/ψπJ/{\psi}{\pi}^{-}, ηcπ{\eta}_{c}{\pi}^{-} Decays with QCD Factorization

    Full text link
    The BcB_{c} {\to} J/ψπJ/{\psi}{\pi}, ηcπ{\eta}_{c}{\pi} decays are studied in the scheme of the QCD factorization approach. The branching ratios are calculated with the asymptotic distribution amplitude of the pion. The charm quark mass effect is considered. We find that the mass effect on the branching ratios is small.Comment: 20 pages, 3 figures, 3 table

    Resonance Measurement of Nonlocal Spin Torque in a Three-Terminal Magnetic Device

    Full text link
    A pure spin current generated within a nonlocal spin valve can exert a spin transfer torque on a nanomagnet. This nonlocal torque enables new design schemes for magnetic memory devices that do not require the application of large voltages across tunnel barriers that can suffer electrical breakdown. Here we report a quantitative measurement of this nonlocal spin torque using spin-torque-driven ferromagnetic resonance. Our measurement agrees well with the prediction of an effective circuit model for spin transport. Based on this model, we suggest strategies for optimizing the strength of nonlocal torque.Comment: 21 pages, 3 figures. Supplement include
    corecore