185 research outputs found

    Periodicity and criticality in the Olami-Feder-Christensen model of earthquakes

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    Characteristic versus critical features of earthquakes are studied on the basis of the Olami-Feder-Christensen model. It is found that the local recurrence-time distribution exhibits a sharp δ\delta-function-like peak corresponding to rhythmic recurrence of events with a fixed ``period'' uniquely determined by the transmission parameter of the model, together with a power-law-like tail corresponding to scale-free recurrence of events. The model exhibits phenomena closely resembling the asperity known in seismology

    Semipolar {n[n¯]01} InGaN/GaN ridge quantum wells (n = 1−3) fabricated by a regrowth technique

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    Semipolar {n[n¯]01} InGaN/GaN quantum wells (QWs) (n = 1−3) are fabricated on top of GaN microstructures, which consist of semipolar {1Ī01} facets. Semipolar planes are obtained via regrowth of three-dimensional structures on (0001) GaN templates under controlled growth conditions. Compared to QWs on {1Ī01} facets, {n[n¯]01} ridge QWs show an intense emission at ∼ 440 nm. Time resolved photoluminescence reveals that the radiative lifetime of excitons in {n[n¯]01} InGaN ridge QWs at 13 K is 310 ps, which is comparable to that in {1Ī01} QWs. The estimated internal quantum efficiency at room temperature is as high as 57%

    Fabrication method of Yb based Oxide matrix for CMC

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    Advances and technical challenges in development of CMC

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    Asperity characteristics of the Olami-Feder-Christensen model of earthquakes

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    Properties of the Olami-Feder-Christensen (OFC) model of earthquakes are studied by numerical simulations. The previous study indicated that the model exhibits ``asperity''-like phenomena, {\it i.e.}, the same region ruptures many times near periodically [T.Kotani {\it et al}, Phys. Rev. E {\bf 77}, 010102 (2008)]. Such periodic or characteristic features apparently coexist with power-law-like critical features, {\it e.g.}, the Gutenberg-Richter law observed in the size distribution. In order to clarify the origin and the nature of the asperity-like phenomena, we investigate here the properties of the OFC model with emphasis on its stress distribution. It is found that the asperity formation is accompanied by self-organization of the highly concentrated stress state. Such stress organization naturally provides the mechanism underlying our observation that a series of asperity events repeat with a common epicenter site and with a common period solely determined by the transmission parameter of the model. Asperity events tend to cluster both in time and in space

    Case of 24-week Fetus Delivered from Mother on Life Support with Brain-death from Suicide Attempt: Ethical Issues Associated with Severe Complications

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    Advances in critical care medicine have made it possible to sustain vital organ systems in brain-dead patients. One clinical scenario besides donor organ retrieval in which a benefit may be gained from continuing life support is pregnancy. A pregnant woman in her late 30ʼs at 23 weeks gestation exhibiting worsening depression was referred to the Department of Psychiatry. One day after admission she attempted suicide by hanging and suffered a cardiopulmonary arrest. A fetal heart beat and fetal motion was confirmed immediately after resuscitation. Three days after admission, an emergency Cesarean section (CS) was performed because of her unstable hemodynamic situation. The baby was born and the mother died after delivery. The baby presented neurological complications. Such a case should be managed collaboratively among professional experts in several medical teams. Consensus and recommendations for the management of similar scenarios may also be adjusted
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