678 research outputs found
Energy state of InGaAs quantum dots on SiO2-patterned vicinal substrate
The optical properties of In0.8Ga0.2As self-assembled quantum dots (SAQDs) grown on GaAs wire structures formed by utilizing SiO2-patterned exact and 5°-off (001) GaAs substrates have been studied with micro-photoluminescence (μ-PL). Single PL peak was occurred for In0.8Ga0.2As SAQDs grown on SiO2-patterned exact (001) GaAs, whereas double PL peaks were showed for SAQDs grown on 5°-off (001) GaAs substrates as the width of the opening windows increased. The power-dependent μ-PL spectra show that the first and second peaks of these double peaks were originated from the well-defined ground and excited state, respectively. These results demonstrated that In0.8Ga0.2As SAQDs selectively grown by utilizing SiO2-patterned 5°-off (001) GaAs substrates have well-defined zero-dimensional quantum states
Self-consistent collective subspaces and diabatic/adiabatic motion in nuclei
We discuss the application of a theory of large-amplitude collective motion
to a simple model mimicking the pairing-plus-quadrupole model of nuclear
physics.Comment: 4 pages, RevTex using graphicx.sty, 1 postscript figures included.
Talk presented at Conference on "Nuclear structure at the extremes" (June 17
- 19, 1998, Lewes, UK
Adaptive Uncertainty-Guided Model Selection for Data-Driven PDE Discovery
We propose a new parameter-adaptive uncertainty-penalized Bayesian
information criterion (UBIC) to prioritize the parsimonious partial
differential equation (PDE) that sufficiently governs noisy spatial-temporal
observed data with few reliable terms. Since the naive use of the BIC for model
selection has been known to yield an undesirable overfitted PDE, the UBIC
penalizes the found PDE not only by its complexity but also the quantified
uncertainty, derived from the model supports' coefficient of variation in a
probabilistic view. We also introduce physics-informed neural network learning
as a simulation-based approach to further validate the selected PDE flexibly
against the other discovered PDE. Numerical results affirm the successful
application of the UBIC in identifying the true governing PDE. Additionally, we
reveal an interesting effect of denoising the observed data on improving the
trade-off between the BIC score and model complexity. Code is available at
https://github.com/Pongpisit-Thanasutives/UBIC.Comment: 17 pages, 15 figure
Adaptive Uncertainty-Penalized Model Selection for Data-Driven PDE Discovery
Thanasutives P., Morita T., Numao M., et al. Adaptive Uncertainty-Penalized Model Selection for Data-Driven PDE Discovery. IEEE Access 12, 13165 (2024); https://doi.org/10.1109/ACCESS.2024.3354819.We propose a new parameter-adaptive uncertainty-penalized Bayesian information criterion (UBIC) to discover the stable governing partial differential equation (PDE) composed of a few important terms. Since the naive use of the BIC for model selection yields an overfitted PDE, the UBIC penalizes the found PDE not only by its complexity but also by its quantified uncertainty. Representing the PDE as the best subset of a few candidate terms, we use Bayesian regression to compute the coefficient of variation (CV) of the posterior PDE coefficients. The PDE uncertainty is then derived from the obtained CV. The UBIC follows the premise that the true PDE shows relatively lower uncertainty when compared with overfitted PDEs. Thus, the quantified uncertainty is an effective indicator for identifying the true PDE. We also introduce physics-informed neural network learning as a simulation-based approach to further validate the UBIC-selected PDE against the other potential PDE. Numerical results confirm the successful application of the UBIC for data-driven PDE discovery from noisy spatio-temporal data. Additionally, we reveal a positive effect of denoising the observed data on improving the trade-off between the BIC score and model complexity
Diabatic and Adiabatic Collective Motion in a Model Pairing System
Large amplitude collective motion is investigated for a model pairing
Hamiltonian containing an avoided level crossing. A classical theory of
collective motion for the adiabatic limit is applied utilising either a
time-dependent mean-field theory or a direct parametrisation of the
time-dependent Schr\"odinger equation. A modified local harmonic equation is
formulated to take account of the Nambu-Goldstone mode. It turns out that in
some cases the system selects a diabatic path. Requantizing the collective
Hamiltonian, a reasonable agreement with an exact calculation for the low-lying
levels are obtained for both weak and strong pairing force. This improves on
results of the conventional Born-Oppenheimer approximation.Comment: 23 pages, 7 ps figures. Latex, uses revtex and graphic
Histomorphological species identification of tiny bone fragments from a Paleolithic site in the Northern Japanese Archipelago
AbstractBone histomorphology is an effective method for species identification of fragmentary osseous remains. The 1997–1998 excavations of the Kashiwadai 1 Upper Paleolithic site (ca. 22–20.5 kyBP) in Hokkaido (the northern island of the Japanese Archipelago) yielded tiny bone fragments, which had been burned to white and broken into pieces less than 1 cm in size, making their species identification by gross morphology alone impossible. For the purpose of species identification, histomorphological analyses were performed on thin sections of the Kashiwadai 1 bone fragments. Compact bone cross sections taken from medium- to large-sized land mammals in the Pleistocene and Holocene Hokkaido were prepared for comparison. The structures of the Kashiwadai 1 samples consisted of secondary osteons and plexiform bone. Consideration of the presence versus absence of plexiform bone and quantitative assessments of osteon sizes and bone cortical thickness allows for distinction between medium-sized deer, large-sized artiodactyls, small- to medium-sized carnivores, large-sized carnivores, elephants, and humans. The histomorphological characteristics of the Kashiwadai 1 samples were quite similar to those of both sika deer and ancient sika deer. A probable conclusion is that medium-sized deer was the primary game hunted by Paleolithic people at the Kashiwadai 1 site. Interestingly, the samples did not include elephant or large-sized artiodactyls, which were the predominant species in other Paleolithic sites of the Japanese Archipelago. This is the first evidence of human hunting medium-sized animals in the Upper Paleolithic period of the Japanese Archipelago based on faunal remains
Successful lung lobectomy for a lung cancer following thoracic endovascular aortic repair for a thoracic aortic aneurysm: report of a case
Lung cancer and a thoracic aortic aneurysm were detected simultaneously in a 79-year-old male patient with diabetes. The aneurysm was first treated by thoracic endovascular aortic repair. A right lower lobectomy was subsequently performed after the blood flow of the bronchial and intercostal arteries was confirmed by computed tomographic angiography. The bronchial stump was covered with an intercostal muscle flap. The patient's postoperative course was uneventful. Thoracic endovascular aortic repair is a useful and less invasive treatment for such cases, but a blood flow evaluation of the aortic branches should be done following this procedure before a lung resection is considered.ArticleSURGERY TODAY. 44(5):940-943 (2014)journal articl
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