7,185 research outputs found
Logistic Knowledge Tracing: A Constrained Framework for Learner Modeling
Adaptive learning technology solutions often use a learner model to trace
learning and make pedagogical decisions. The present research introduces a
formalized methodology for specifying learner models, Logistic Knowledge
Tracing (LKT), that consolidates many extant learner modeling methods. The
strength of LKT is the specification of a symbolic notation system for
alternative logistic regression models that is powerful enough to specify many
extant models in the literature and many new models. To demonstrate the
generality of LKT, we fit 12 models, some variants of well-known models and
some newly devised, to 6 learning technology datasets. The results indicated
that no single learner model was best in all cases, further justifying a broad
approach that considers multiple learner model features and the learning
context. The models presented here avoid student-level fixed parameters to
increase generalizability. We also introduce features to stand in for these
intercepts. We argue that to be maximally applicable, a learner model needs to
adapt to student differences, rather than needing to be pre-parameterized with
the level of each student's ability
Magnetic Ground State of PrLaCeCuO with Varied Oxygen Depletion Probed by Muon Spin Relaxation
The magnetic ground state of an electron-doped cuprate superconductor
PrLaCeCuO () has been
studied by means of muon spin rotation/relaxation (\msr) over a wide variety of
oxygen depletion, . Appearance of weak random magnetism
over entire crystal volume has been revealed by a slow exponential relaxation.
The absence of -dependence for the random magnetism and the multiplet
pattern of muon Knight shift at higher fields strongly suggest that the random
moments are associated with excited Pr ions under crystal electric
field.Comment: 6 pages, 4 figures, submitted to J. Phys. Soc. Jp
Recent Progress in Heavy Quark Physics
Some of the recent progress in heavy quark physics is reviewed. Special
attention is paid to inclusive methods for determining Vub and factorization in
nonleptonic B decays. Theoretical predictions for top-antitop production near
threshold are also discussed.Comment: talk given at 2001 Lepton Photon Meeting, 10 pages, 5 figure
Hybridization gap versus hidden order gap in URuSi as revealed by optical spectroscopy
We present the in-plane optical reflectance measurement on single crystals of
URuAs. The study revealed a strong temperature-dependent spectral
evolution. Above 50 K, the low frequency optical conductivity is rather flat
without a clear Drude-like response, indicating a very short transport life
time of the free carriers. Well below the coherence temperature, there appears
an abrupt spectral weight suppression below 400 cm, yielding evidence
for the formation of a hybridization energy gap arising from the mixing of the
conduction electron and narrow f-electron bands. A small part of the suppressed
spectral weight was transferred to the low frequency side, leading to a narrow
Drude component, while the majority of the suppressed spectral weight was
transferred to the high frequency side centered near 4000 cm. Below the
hidden order temperature, another very prominent energy gap structure was
observed, which leads to the removal of a large part of the Drude component and
a sharp reduction of the carrier scattering rate. The study revealed that the
hybridization gap and the hidden orger gap are distinctly different: they occur
at different energy scales and exhibit completely different spectral
characteristics.Comment: 5 page
Randomised controlled trial comparing rubber band ligation with stapled haemorrhoidopexy for Grade II circumferential haemorrhoids : Long-term results
Peer reviewedPostprin
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