21,732 research outputs found
Quality Indicators Guiding Secondary Career and Technical Education Programs of Study
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
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
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
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
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
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 , Decays with QCD Factorization
The , 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
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
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