104 research outputs found
Information-Theoretic Characterization of the Generalization Error for Iterative Semi-Supervised Learning
Using information-theoretic principles, we consider the generalization error
(gen-error) of iterative semi-supervised learning (SSL) algorithms that
iteratively generate pseudo-labels for a large amount of unlabelled data to
progressively refine the model parameters. In contrast to most previous works
that {\em bound} the gen-error, we provide an {\em exact} expression for the
gen-error and particularize it to the binary Gaussian mixture model. Our
theoretical results suggest that when the class conditional variances are not
too large, the gen-error decreases with the number of iterations, but quickly
saturates. On the flip side, if the class conditional variances (and so amount
of overlap between the classes) are large, the gen-error increases with the
number of iterations. To mitigate this undesirable effect, we show that
regularization can reduce the gen-error. The theoretical results are
corroborated by extensive experiments on the MNIST and CIFAR datasets in which
we notice that for easy-to-distinguish classes, the gen-error improves after
several pseudo-labelling iterations, but saturates afterwards, and for more
difficult-to-distinguish classes, regularization improves the generalization
performance.Comment: 52 pages, 17 figure
Extraction of Electron Self-Energy and Gap Function in the Superconducting State of Bi_2Sr_2CaCu_2O_8 Superconductor via Laser-Based Angle-Resolved Photoemission
Super-high resolution laser-based angle-resolved photoemission measurements
have been performed on a high temperature superconductor Bi_2Sr_2CaCu_2O_8. The
band back-bending characteristic of the Bogoliubov-like quasiparticle
dispersion is clearly revealed at low temperature in the superconducting state.
This makes it possible for the first time to experimentally extract the complex
electron self-energy and the complex gap function in the superconducting state.
The resultant electron self-energy and gap function exhibit features at ~54 meV
and ~40 meV, in addition to the superconducting gap-induced structure at lower
binding energy and a broad featureless structure at higher binding energy.
These information will provide key insight and constraints on the origin of
electron pairing in high temperature superconductors.Comment: 4 pages, 4 figure
Viscosity approximation methods for nonexpansive nonself-mappings without boundary conditions
Construction of Vascular Tissues with Macro-Porous Nano-Fibrous Scaffolds and Smooth Muscle Cells Enriched from Differentiated Embryonic Stem Cells
Vascular smooth muscle cells (SMCs) have been broadly used for constructing tissue-engineered blood vessels. However, the availability of mature SMCs from donors or patients is very limited. Derivation of SMCs by differentiating embryonic stem cells (ESCs) has been reported, but not widely utilized in vascular tissue engineering due to low induction efficiency and, hence, low SMC purity. To address these problems, SMCs were enriched from retinoic acid induced mouse ESCs with LacZ genetic labeling under the control of SM22α promoter as the positive sorting marker in the present study. The sorted SMCs were characterized and then cultured on three-dimensional macro-porous nano-fibrous scaffolds in vitro or implanted subcutaneously into nude mice after being seeded on the scaffolds. Our data showed that the LacZ staining, which reflected the corresponding SMC marker SM22α expression level, was efficient as a positive selection marker to dramatically enrich SMCs and eliminate other cell types. After the sorted cells were seeded into the three-dimensional nano-fibrous scaffolds, continuous retinoic acid treatment further enhanced the SMC marker gene expression level while inhibited pluripotent maker gene expression level during the in vitro culture. Meanwhile, after being implanted subcutaneously into nude mice, the implanted cells maintained the positive LacZ staining within the constructs and no teratoma formation was observed. In conclusion, our results demonstrated the potential of SMCs derived from ESCs as a promising cell source for therapeutic vascular tissue engineering and disease model applications
A new iteration method for variational inequalities on the set of common fixed points for a finite family of quasi-pseudocontractions in Hilbert spaces
Synthesis of graphene/methylene blue/gold nanoparticles composites based on simultaneous green reduction, in situ growth and self-catalysis
Interdisciplinary topics of information science: a study based on the terms interdisciplinarity index series
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