10,310 research outputs found
A Critical Analysis of Structural Contradictions in Open and Distance Higher Education Using Cultural-Historical Activity Theory
Drawing upon cultural-historical activity theory, this research analyzed the structural contradictions existing in a variety of educational activities among a group of alienated adult students in open and distance higher education
Towards an Interaction-based Integration of MKM Services into End-User Applications
The Semantic Alliance (SAlly) Framework, first presented at MKM 2012, allows
integration of Mathematical Knowledge Management services into typical
applications and end-user workflows. From an architecture allowing invasion of
spreadsheet programs, it grew into a middle-ware connecting spreadsheet, CAD,
text and image processing environments with MKM services. The architecture
presented in the original paper proved to be quite resilient as it is still
used today with only minor changes.
This paper explores extensibility challenges we have encountered in the
process of developing new services and maintaining the plugins invading
end-user applications. After an analysis of the underlying problems, I present
an augmented version of the SAlly architecture that addresses these issues and
opens new opportunities for document type agnostic MKM services.Comment: 14 pages, 7 figure
Deterministic amplification of Schroedinger cat states in circuit quantum electrodynamics
We propose a dynamical scheme for deterministically amplifying photonic
Schroedinger cat states based on a set of optimal state-transfers. The scheme
can be implemented in strongly coupled qubit-cavity systems and is well suited
to the capabilities of state of the art superconducting circuits. The ideal
analytical scheme is compared with a full simulation of the open
Jaynes-Cummings model with realistic device parameters. This amplification tool
can be utilized for practical quantum information processing in non-classical
continuous-variable states.Comment: A revised manuscript has 6 figure
Neutrino masses and mixing from S4 flavor twisting
We discuss a neutrino mass model based on the S4 discrete symmetry where the
symmetry breaking is triggered by the boundary conditions of the bulk
right-handed neutrino in the fifth spacial dimension. While the symmetry
restricts bare mass parameters to flavor-diagonal forms, the viable mixing
angles emerge from the wave functions of the Kaluza-Klein modes which carry
symmetry breaking effect. The magnitudes of the lepton mixing angles,
especially the reactor angle is related to the neutrino mass patterns and the
model will be tested in future neutrino experiments, e.g., an early (late)
discovery of the reactor angle favors the normal (inverted) hierarchy. The size
of extra dimension has a connection to the possible mass spectrum; a small
(large) volume corresponds to the normal (inverted) mass hierarchy.Comment: 22 pages, 3 figures; added references for section
Q2 Dependence of Quadrupole Strength in the γ*p→Δ+(1232)→pπ0 Transition
Models of baryon structure predict a small quadrupole deformation of the nucleon due to residual tensor forces between quarks or distortions from the pion cloud. Sensitivity to quark versus pion degrees of freedom occurs through the Q2 dependence of the magnetic (M1+), electric (E1+), and scalar (S1+) multipoles in the γ∗p→Δ+→pπ0 transition. We report new experimental values for the ratios E1+/M1+ and S1+/M1+ over the range Q2=0.4–1.8GeV2, extracted from precision p(e,e′p)π0 data using a truncated multipole expansion. Results are best described by recent unitary models in which the pion cloud plays a dominant role
Local Hall effect in hybrid ferromagnetic/semiconductor devices
We have investigated the magnetoresistance of ferromagnet-semiconductor
devices in an InAs two-dimensional electron gas system in which the magnetic
field has a sinusoidal profile. The magnetoresistance of our device is large.
The longitudinal resistance has an additional contribution which is odd in
applied magnetic field. It becomes even negative at low temperature where the
transport is ballistic. Based on the numerical analysis, we confirmed that our
data can be explained in terms of the local Hall effect due to the profile of
negative and positive field regions. This device may be useful for future
spintronic applications.Comment: 4 pages with 4 fugures. Accepted for publication in Applied Physics
Letter
Measurement of the polarized structure function σLT′ for pion electroproduction in the Roper-resonance region
The polarized longitudinal-transverse structure function σLT′ measures the interference between real and imaginary amplitudes in pion electroproduction and can be used to probe the coupling between resonant and nonresonant processes. We report new measurements of σLT′ in the N(1440)12+ (Roper) resonance region at Q2=0.40 and 0.65GeV2 for both the π0p and π+n channels. The experiment was performed at Jefferson Lab with the CEBAF Large Acceptance Spectrometer (CLAS) using longitudinally polarized electrons at a beam energy of 1.515 GeV. Complete angular distributions were obtained and are compared to recent phenomenological models. The σLT′(π+n) channel shows a large sensitivity to the Roper-resonance multipoles M1− and S1− and provides new constraints on models of resonance formation
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