Interplate coupling in the southernmost extent of the northeast Japan subduction zone (east off-Kanto, Japan) is investigated in detail using a large data set of small repeating earthquakes. In this ...region of the trench-trench-trench type triple junction, the subducting Pacific plate is in contact with two different overlying plates (the North American and Philippine Sea plates). The border between the two overlying plates extending northwestward from the triple junction is identified along the upper surface of the Pacific plate based on the slip vectors of many interplate events including small repeating earthquakes. The interplate coupling coefficient estimated from the cumulative slip of small repeating earthquakes for the period from 1993 to 2007 reveals a distinct change from south (ca. 0.3) to north (ca. 0.7) across the border. This border also corresponds to the southern limit of the source areas of M>7 interplate earthquakes in the last 80 years along the Japan trench, again indicating the stronger coupling to the north. We also investigate hypocenter distribution and seismic velocity structure along the plate boundary from a large number of travel-time data obtained from the nationwide seismograph network. The results reveal a distinct low-velocity zone just above the Pacific plate and low seismicity along the plate boundary in the region overlain by the Philippine Sea plate, whereas there are no low-velocity zones and the seismicity is high in the region overlain by the North American plate. These observations imply that the geological difference of overlying plate controls large-scale coupling at the plate interface.
Understanding of postseismic deformation following great subduction zone earthquakes is complicated by the combined effects of viscoelastic relaxation of earthquake‐induced stresses in the upper ...mantle and time‐dependent afterslip on the megathrust. We integrate geodetic observations and constraints on afterslip from small repeating earthquakes on the megathrust to better distinguish contributions from these two postseismic processes. We have developed a three‐dimensional, spherical viscoelastic finite element model to study the postseismic deformation of the 2011 Mw9.0 Tohoku earthquake that has been recorded at unprecedented high resolution in space and time. We model stress‐driven afterslip in a 2 km thick weak shear zone away from historic rupture zones on the megathrust. We model both the viscoelastic relaxation of the upper mantle and shear zone deformation with a transient Burgers body rheology. The transient Kelvin viscosity is assumed to be one order of magnitude lower than that of the Maxwell viscosity. Viscoelastic relaxation of the mantle wedge alone causes postseismic uplift and seaward motion in the upper plate, opposite to the pattern from relaxation of just the oceanic upper mantle. Afterslip on the fault produces uplift updip of the afterslip zone and subsidence over its downdip edge and mostly seaward motion above the afterslip zone. The best fit Maxwell viscosity of the shear zone at depths ≤50 km is 1017 Pa s, constrained by afterslip estimates from repeating earthquakes. The optimal viscosities of the deep weak shear zone, continental mantle wedge, and oceanic upper mantle are determined to be 5 × 1017 Pa s, 3 × 1019 Pa s, and 5 × 1019 Pa s, respectively. The stress‐driven afterslip in the shear zone is up to ~3.5 m in the first 2 years after the earthquake, equivalent to an Mw8.4. Our model reproduces the first‐order pattern of the GPS observations both in horizontal and in vertical directions. Seafloor geodetic observations of subsidence and landward motions near the high‐slip zone of the earthquake provide evidence for a low‐viscosity asthenosphere below the oceanic lithosphere.
Key Points
Stress‐driven, time‐dependent afterslip can be successfully simulated by a narrow weak shear zone
The upper mantle rheology can be determined through viscoelastic postseismic GPS observations
Higher‐order deformation heterogeneity may be explained by higher‐order rheology heterogeneity
The temporal evolution of intermediate‐depth seismicity before and after the 2011 M9.0 Tohoku‐oki earthquake reveals interactions between plate interface slip and deformation in the subducting slab. ...We investigate seismicity rate changes in the upper and lower planes of the double seismic zone beneath northeast Japan using both a β statistic approach and a temporal epidemic type aftershock sequence model. We do not observe an anomalous precursory increase in intermediate‐depth earthquake activity preceding the mainshock; however, following the mainshock, we observe a rate increase for the intermediate‐depth earthquakes in the upper plane. The average ratio of upper plane to lower plane activity and the mean deep aseismic slip rate both increased by factor of 2. An increase of downdip compression in the slab resulting from coseismic and postseismic deformation enhanced seismicity in the upper plane, which is dominated by events accommodating downdip shortening from plate unbending.
Introduction
The clinical benefit of vitamin D receptor activators (VDRA) in patients with well‐controlled secondary hyperparathyroidism undergoing dialysis remains unclear.
Methods
This post hoc ...analysis of the LANDMARK study investigates if VDRA use is associated with cardiovascular benefits. Data of 2135 patients undergoing hemodialysis who were at risk for vascular calcification were analyzed using a Cox proportional hazards model with propensity‐score matching.
Results
The hazard ratio (HR) for VDRA use was 0.99 (95% confidence interval CI: 0.67–1.46; p = 0.945) for cardiovascular events and 0.89 (95% CI: 0.62–1.28; p = 0.541) for all‐cause mortality at baseline. Among patients who always used VDRA, the HR was 1.12 (95% CI: 0.67–1.89; p = 0.666) for cardiovascular events and 1.11 (95% CI: 0.67–1.85; p = 0.688) for all‐cause mortality compared to those who never used VDRA.
Conclusion
The use of VDRA does not reduce the risks of cardiovascular events or all‐cause mortality in patients on dialysis with well‐controlled secondary hyperparathyroidism.
Ni–Al layered double hydroxide (LDH) was prepared on a steel plate and fumed alumina by the liquid phase deposition (LPD) method with NO2− inserted between the layers for rust prevention, and its ...corrosion-inhibition effect was investigated. Anion exchange of the synthesized LDH was carried out by immersing it in aqueous KOH and NaNO2 solutions, separately. The composition of the obtained Ni–Al LDH is typically Ni(II)0.69Al(III)0.31(OH)2OH0.31 in OH−-type LDH. Electrochemical measurements revealed the expansion of the passive area and a decrease in the corrosion current in the sample mixed with LDH, compared to the case with the pure polyacrylic gel sample. In particular, the corrosion current was reduced to less than half of the original in the samples mixed with NO2−–LDH. For the polyacrylic gel containing LDH, the anodic current was suppressed at all concentrations of the aqueous NaCl solution, and the corrosion current was approximately the same as the result of the polarization measurement. The corrosion-inhibiting effects due to Cl− absorption and NO2− release were confirmed. A good rust preventive effect was also observed in the hydrous LDH gel sheet intended to be exposed to the atmosphere where an arbitrary amount of Cl− ions is dissolved.
The aftershock distribution of the 1933 Sanriku-oki outer trench earthquake is estimated by using modern relocation methods and a newly developed velocity structure to examine the spatial extent of ...the source-fault and the possibility of a triggered interplate seismicity. In this study, we first examined the regional data quality of the 1933 earthquake based on smoked-paper records and then relocated the earthquakes by using the 3-D velocity structure and double-difference method. The improvements of hypocentre locations using these methods were confirmed by the examination of recent earthquakes that are accurately located based on ocean bottom seismometer data. The results show that the 1933 aftershocks occurred under both the outer- and inner-trench-slope regions. In the outer-trench-slope region, aftershocks are distributed in a ∼280-km-long area and their depths are shallower than 50 km. Although we could not constrain the fault geometry from the hypocentre distribution, the depth distribution suggests the whole lithosphere is probably not under deviatoric tension at the time of the 1933 earthquake. The occurrence of aftershocks under the inner trench slope was also confirmed by an investigation of waveform frequency difference between outer and inner trench earthquakes as recorded at Mizusawa. The earthquakes under the inner trench slope were shallow (depth ≦30 km) and the waveforms show a low-frequency character similar to the waveforms of recent, precisely located earthquakes in the same area. They are also located where recent activity of interplate thrust earthquakes is high. These suggest that the 1933 outer-trench-slope main shock triggered interplate earthquakes, which is an unusual case in the order of occurrence in contrast with the more common pairing of a large initial interplate shock with subsequent outer-slope earthquakes. The off-trench earthquakes are distributed about 80 km width in the trench perpendicular direction. This wide width cannot be explained from a single high-angle fault confined at a shallow depth (depth ≦50 km). The upward motion of the 1933 tsunami waveform records observed at Sanriku coast also cannot be explained from a single high-angle west-dipping normal fault. If we consider additional fault, involvement of high-angle, east-dipping normal faults can better explain the tsunami first motion and triggering of the aftershock in a wide area under the outer trench slope. Therefore multiple off-trench normal faults may have activated during the 1933 earthquake. We also relocated recent (2001–2012) seismicity by the same method. The results show that the present seismicity in the outer-trench-slope region can be divided into several groups along the trench. Comparison of the 1933 rupture dimensions based on our aftershock relocations with the morphologies of fault scarps in the outer trench slope suggest that the rupture was limited to the region where fault scarps are largely trench parallel and cross cut the seafloor spreading fabric. These findings imply that bending geometry and structural segmentation of the incoming plate largely controls the spatial extent of the 1933 seismogenic faulting. In this shallow rupture model for this largest outer trench earthquake, triggered seismicity in the forearc and structural control of faulting represent an important deformation styles for off-trench and shallow megathrust zones.
Background
It is necessary to re-examine the optimal phosphate (P) and calcium (Ca) target values in the contemporary management of chronic kidney disease–mineral and bone disorder to reduce the ...risks of cardiovascular events in patients receiving hemodialysis.
Methods
We performed a post-hoc analysis of the LANDMARK study. The outcomes were defined as cardiovascular events and all-cause death. Data from 2135 patients receiving hemodialysis at risk of vascular calcification were analyzed using a time-dependent Cox proportional hazard model adjusted for background factors.
Results
On the hazard ratio (HR) curve, the ranges where the lower 95% confidence interval (CI) were below the minimum of HR (= 1.00) were as follows: P = 3.5–5.5 mg/dL; albumin-adjusted Ca < 9.1 mg/dL for cardiovascular events; and P = 3.6–5.3 mg/dL; albumin-adjusted Ca < 9.1 mg/dL for all-cause mortality. In stratified analysis, the HRs for cardiovascular events in P < 3.5 mg/dL and P ≥ 5.5 mg/dL were similar to that of P = 3.5–5.5 mg/dL (
P
≥ 0.05), and albumin-adjusted Ca ≥ 9.1 mg/dL had higher HR than values < 9.1 mg/dL 1.30 (95% CI 1.00–1.68;
P
= 0.046). For all-cause mortality, the HR in P < 3.6 mg/dL was higher than that in P = 3.6–5.3 mg/dL 1.76 (95% CI 1.25–2.48;
P
= 0.001), while the HRs between P ≥ 5.3 mg/dL and P = 3.6–5.3 mg/dL as well as those between albumin-adjusted Ca ≥ 9.1 and < 9.1 mg/dL were not significantly different (
P
≥ 0.05).
Conclusions
Managing albumin-adjusted Ca < 9.1 mg/dL may reduce the cardiovascular risk among patients undergoing hemodialysis. Hypophosphatemia < 3.6 mg/dL may be associated with mortality.
Immune checkpoint inhibitors (ICIs), particularly anti-PD-1 antibody, have dramatically changed cancer treatment; however, fatal immune-related adverse events (irAEs) can develop. Here, we describe a ...severe case of sclerosing cholangitis-like irAE. We report the use of 3 immunosuppressive agents that resulted in the death of the patient due to treatment inefficacy. According to a postmarketing study of nivolumab, the frequency of ICI-related sclerosing cholangitis is 0.27% and that of ICI-related cholangitis is 0.20%. There have been 4 case reports of sclerosing cholangitis-like irAE, with imaging findings, including typical intrahepatic bile duct beaded constriction in primary sclerosing cholangitis. Treatment starts with prednisolone and is combined with an immunosuppressant in refractory cases. There are no reports of severe cases that ultimately led to death.
The patient is a 64-year-old male with Stage IV squamous cell lung carcinoma; he was hospitalized with abdominal pain and elevation of aspartate transaminase and alanine transaminase, approximately 4 months after ICI administration was suspended. This occurred because the patient treated with nivolumab as the second-line chemotherapy and developed type 1 diabetes mellitus after 11 courses.
A grade 3 increase in bilirubin was observed and he was diagnosed with sclerosing cholangitis, based on magnetic resonance cholangiopancreatography imaging and pathological findings of the liver and bile duct.
Prednisolone, mycophenolate mofetil, and tacrolimus combination therapy was administered.
The treatment was difficult and failed. He died from liver failure 8 months after diagnosis. In this case, hepatitis and cholangitis, mainly alanine transaminase-dominant liver disorder, developed in the early stages of irAEs. Although he showed some improvement after prednisolone administration, bilirubin levels began rising again, and sclerosing cholangitis did not improve even with the use of 3 immunosuppressive agents recommended by the ESMO Clinical Practice Guidelines for immune-related hepatotoxicity management. Although the antitumor effect showed a complete response, liver failure led to death.
This is the first case report on the ineffectiveness of triple immunosuppressant combination therapy recommended by the guidelines for immune-related hepatotoxicity. It is necessary to develop more appropriate treatment for severe sclerosing cholangitis-like irAE based on the robust evidence.
We investigated spatiotemporal change in the interplate seismic activity following the 2011 Tohoku‐oki earthquake (M9.0) in the region where interseismic interplate coupling was relatively weak and ...large postseismic slip was observed. We classified earthquakes by their focal mechanisms to identify the interplate events and conducted hypocenter relocation to examine the detailed spatiotemporal distribution of interplate earthquakes in the mostly creeping area. The results show that many interplate earthquakes, including M ~ 6 events, emerged immediately after the Tohoku‐oki earthquake in areas where very few interplate earthquakes had been observed in the 88 previous years. The emergent earthquakes include repeating sequences, and the extremely long quiescence of small to moderate earthquakes before the Tohoku‐oki earthquake suggests that the source areas for the post‐M9 events slipped aseismically during the quiescence. The repeaters' magnitudes decayed over time following the Tohoku‐oki earthquake and some sequences disappeared within a year. The emergence of interplate earthquakes suggests that areas where aseismic slip had been dominant before the Tohoku‐oki earthquake started to cause seismic slip after the earthquake, probably due to the increased loading rate from the afterslip. The magnitude decrease and disappearance of repeaters can be interpreted as shrinkage in seismic areas around the repeaters' sources as the loading rate decreased due to the afterslip decay over time. These observations suggest that changes in the loading rate can cause slip behavior transition between seismic and aseismic. This indicates that such loading‐rate‐dependent slip behavior plays an important role in the spatiotemporal distribution of earthquakes in interplate seismogenic zones.
Key Points
We investigated temporal changes in interplate seismicity due to the 2011 Tohoku‐oki earthquake in a fault‐creep dominant area
We observed coseismic emergence and subsequent disappearance of interplate earthquakes including repeating earthquakes
The observations can be explained by slip behavior transition between seismic and aseismic depending on the loading rate
An unprecedented single-step synthesis of enyne derivatives through Pd-catalyzed arylalkynylation of aryl iodides, internal alkynes, and alkynylsilanes is described.
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