65 research outputs found
Statistical Properties of the Inter-occurrence Times in the Two-dimensional Stick-slip Model of Earthquakes
We study earthquake interval time statistics, paying special attention to
inter-occurrence times in the two-dimensional (2D) stick-slip (block-slider)
model. Inter-occurrence times are the time interval between successive
earthquakes on all faults in a region. We select stiffness and friction
parameters as tunable parameters because these physical quantities are
considered as essential factors in describing fault dynamics. It is found that
inter-occurrence time statistics depend on the parameters. Varying stiffness
and friction parameters systematically, we optimize these parameters so as to
reproduce the inter-occurrence time statistics in natural seismicity. For an
optimal case, earthquakes produced by the model obey the Gutenberg-Richter law,
which states that the magnitude-frequency distribution exhibits the power law
with an exponent approximately unity.Comment: 8 pages, 5 figures, contribution to the conference proceeding of
21COE International Symposium, Tokyo, Japan Sept 13-14 200
A danger of induction of Brugada syndrome during pill-in-the-pocket therapy for paroxysmal atrial fibrillation
Rhythm control therapy by sodium channel blockers is widely performed for the treatment of paroxysmal atrial fibrillation. Here, we present a case of acquired Brugada syndrome by pill-in-the-pocket treatment using pilsicainide. It is important that this therapy should be applied only after confirming the drug safety to the patients
Evaluation of internal margins for prostate for step and shoot intensity‐modulated radiation therapy and volumetric modulated arc therapy using different margin formulas
[Purpose] This feasibility study evaluated the intra-fractional prostate motion using an ultrasound image-guided system during step and shoot intensity-modulated radiation therapy (SS-IMRT) and volumetric modulated arc therapy (VMAT). Moreover, the internal margins (IMs) using different margin formulas were calculated. [Methods] Fourteen consecutive patients with prostate cancer who underwent SS-IMRT (n = 5) or VMAT (n = 9) between March 2019 and April 2020 were considered. The intra-fractional prostate motion was observed in the superior–inferior (SI), anterior–posterior (AP), and left–right (LR) directions. The displacement of the prostate was defined as the displacement from the initial position at the scanning start time, which was evaluated using the mean ± standard deviation (SD). IMs were calculated using the van Herk and restricted maximum likelihood (REML) formulas for SS-IMRT and VMAT. [Results] For SS-IMRT, the maximum displacements of the prostate motion were 0.17 ± 0.18, 0.56 ± 0.86, and 0.18 ± 0.59 mm in the SI, AP, and LR directions, respectively. For VMAT, the maximum displacements of the prostate motion were 0.19 ± 0.64, 0.22 ± 0.35, and 0.14 ± 0.37 mm in the SI, AP, and LR directions, respectively. The IMs obtained for SS-IMRT and VMAT were within 2.3 mm and 1.2 mm using the van Herk formula and within 1.2 mm and 0.8 mm using the REML formula. [Conclusions] This feasibility study confirmed that intra-fractional prostate motion was observed with SS-IMRT and VMAT using different margin formulas. The IMs should be determined according to each irradiation technique using the REML margin
Preparation of highly active AlSBA-15-supported platinum catalyst for thiophene hydrodesulfurization
The catalytic activities of various noble metals (Pt, Pd, Rh, and Ru) supported on siliceous SBA-15 and Al-containing SBA-15 (AlSBA-15) for hydrodesulfurization (HDS) of thiophene at 350 C were investigated. AlSBA-15 was prepared by a grafting method using aluminum isopropoxide (Al(OC3H7)3) hexane solution. The HDS activity of Pt/AlSBA-15 catalyst was the highest among those of various supported noble metal catalysts, and this activity was higher than that of commercial CoMo/Al2O3 HDS catalyst. The catalysts were characterized by XRD analysis, hydrogen adsorption, 2-propanol dehydration, cumene cracking, and FT-IR. Dispersion of Pt on SBA-15 was remarkably enhanced by Al grafting. It was revealed that the acidity of AlSBA-15 was higher than that of SBA-15. Furthermore, Brønsted acid sites were observed on AlSBA-15. FT-IR spectra of thiophene adsorbed on AlSBA-15 indicate that thiophene molecules interact with Brønsted acid sites on the surface of AlSBA-15 and that the strength of this interaction was stronger than that of SBA-15. Based on these results, thiophene molecules activated on Brønsted acid site of AlSBA-15 and hydrogen molecules activate to form spillover hydrogen on Pt particles in Pt/AlSBA-15 catalyst in the HDS of thiophene
The Weibull - log Weibull Transition of the Inter-occurrence time statistics in the two-dimensional Burridge-Knopoff Earthquake model
In analyzing synthetic earthquake catalogs created by a two-dimensional
Burridge-Knopoff model, we have found that a probability distribution of the
interoccurrence times, the time intervals between successive events, can be
described clearly by the superposition of the Weibull distribution and the
log-Weibull distribution. In addition, the interoccurrence time statistics
depend on frictional properties and stiffness of a fault and exhibit the
Weibull - log Weibull transition, which states that the distribution function
changes from the log-Weibull regime to the Weibull regime when the threshold of
magnitude is increased. We reinforce a new insight into this model; the model
can be recognized as a mechanical model providing a framework of the Weibull -
log Weibull transition.Comment: 11 pages, 7 figure
Noise robust automatic charge state recognition in quantum dots by machine learning and pre-processing, and visual explanations of the model with Grad-CAM
Charge state recognition in quantum dot devices is important in preparation
of quantum bits for quantum information processing. Towards auto-tuning of
larger-scale quantum devices, automatic charge state recognition by machine
learning has been demonstrated. In this work, we propose a simpler method using
machine learning and pre-processing. We demonstrate the operation of the charge
state recognition and evaluated an accuracy high as 96%. We also analyze the
explainability of the trained machine learning model by gradient-weighted class
activation mapping (Grad-CAM) which identifies class-discriminative regions for
the predictions. It exhibits that the model predicts the state based on the
change transition lines, indicating human-like recognition is realized.Comment: 15 pages, 6 figure
Seismic Statistics : Universality and Interim Report on the 3. 11 Earthquake (2011) in Fukushima-Miyagi Area
We mainly study three empirical laws in earthquake statistics; the Omori formula in the aftershock frequency, the Gutenberg-Richter formula for the magnitude, and the interoccurrence time distribution, and we show a possibility to refine and to unify them by carrying out with the data analysis for natural earthquakes in Japan, Taiwan, and South California. Especially in the analysis of the 3.11 EQ (2011) in Fukushima-Miyagi area, firstly it is emphasized that the Omori formula is generalized to express the magnitude-dependent form, and that the Omori coefficient reveals the same behavior as the Gutenberg-Richter(GR)law in the nonstationary regime after the big shock. Next, the multi-fractal diagram, that connects the GR law and the Weibull distribution for interoccurrence times, is studied to characterize the shock sequences before and after the main shock. A universal relation is well confirmed in the long stationary regime before the main shock, but in the nonstationary regime such as the foreshock region and the aftershock region, the multi-fractal diagram reveals big deviations from the stationary case. In spite of those deviations, it is shown that
the empirical laws are approximately confirmed even in the nonstationary regime. Lastly,the moving ensembles are used to describe the temporal change of the multi-fractal diagram. We could not find out any signals to suggest the occurrence of the big shock in statistical parameters, but the multi-fractal diagram obeys the time-dependent universal relation in the nonstationary regime. These results imply that the universality is also existing even in the nonequilibrium moving ensemble. In relation to these remarkable points, we will discuss some theoretical conjectures to seismic statistics, which enable us to understand the origin of statistical laws of earthquakes beyond the traditional ergodic-theoretical interpretation
- …