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Despite endoscopic thyroid surgery contributing to excellent cosmetic outcomes, it requires longer surgical time than open surgery. This study evaluates the factors associated with operative time in video-assisted neck surgery.

The 2018 Mj6.7 Hokkaido Eastern Iburi earthquake (Iburi earthquake) occurred near the eastern boundary fault zone of the Ishikari lowlands, which is composed of a northern and southern fault. Aftershock distribution suggests the existence of a previously unknown fault (the Shallow Iburi (SI) fault) at a shallower extension of the Iburi earthquake fault. In the present study, we examined the seismic potential of the northern, southern, and SI faults based on seismological analysis and numerical simulations. The aftershock focal mechanisms infer the present-day stress field that is characterized by an ENE–SWS compression around the target faults. Slip tendency analysis shows that all target faults originally have high slip potential under the estimated stress field. We, therefore, evaluated earthquake occurrence potential on the target faults influenced by the Iburi earthquake based on the Coulomb stress (ΔCFF). We consider postseismic viscoelastic deformation in the viscoelastic medium with a three-dimensional structure. The present paper shows one possible scenario based on a model incorporating information currently available. The most of the entire SI fault was brought closer to rupture just after the earthquake, indicated by the positive ΔCFF, which is consistent with the activation of seismicity in this region. The ΔCFF continues to increase over many years after the earthquake, which may imply a growing risk of seismic hazards along the SI fault. The distribution of the ΔCFF along the southern fault and the southern half of the northern fault is characterized by a similar depth-dependent pattern. The faults were brought closer to rupture just after the earthquake, indicated by the positive ΔCFF, except for mid-depths along the faults. Then, the ΔCFF increases at shallow depths for a few decades after the earthquake, which suggests a continuous build-up of stress. Although the ΔCFF decreases at the deep depths for a few decades after the earthquake, it is insufficient to return the stress level to that before the earthquake. These results suggest that all target faults are in the state of increasing seismic risk after the Iburi earthquake.

The 1944 Tonankai and 1946 Nankai megathrust earthquakes are likely to have been immediately preceded by a huge slow slip event (SSE) in the deeper brittle‐to‐ductile transition zone, which accumulates slip of a meter or more within several days. The present study investigates the interaction between such huge SSEs and the characteristic earthquakes through earthquake cycle simulations obeying the rate‐ and state‐dependent friction. To simulate huge SSEs, we employ a cutoff velocity (Vcx) above which the friction changes from velocity weakening to velocity strengthening. We assume that Vcxdecreases from 10 to 10−9m/s with depth over the transition zone located between 20‐ and 35‐km depths. Depending on the characteristic slip distance Lof rate and state friction, simulation results showed three patterns of earthquake nucleation. If Lis small, an SSE in the transition zone directly grows into an earthquake without experiencing a separate nucleation at the brittle zone (brittle nucleation). If Lis moderate, an SSE triggers brittle nucleation, which develops into an earthquake. If Lis large, an SSE occurs but ceases without triggering an earthquake nor brittle nucleation, then slip deficit accumulates further to finally start brittle nucleation without the direct help of SSE, and an earthquake occurs without a large precursor. In addition, isolated huge SSEs, resembling precursory ones, occur in all cases, at most a few times per cycle. We investigate the nucleation of characteristic earthquakes in simulated cycles involving deep huge SSEsThree distinct nucleation patterns were found; two involve a huge SSE; a huge SSE does not necessarily trigger an earthquakeSSEs and earthquake nucleation grow huge because of a unique slip profile characterized by a flatter maximum than an ellipse

Single inner hair cells of the guinea pig cochlea were isolated using enzymatic and mechanical techniques. the intracellular free calcium ion concentrations ([Ca2]i) of the isolated inner hair cells were determined using the Ca2sensitive dye fura-2 and digital imaging microscopy. in the presence of 1 um ionomycin, a Ca2ionophore, there was an irreversible increase in [Ca2]i. the 150 mM KC1 stimulation, which induces a depolarization, resulted in a temporary increase in [Ca2]i. This increase in [Ca2]i was not observed under conditions of depolarization, in Ca2-free medium. These observations are interpreted to mean that the increased [Ca2]i during membrane depolarization mainly originates from an influx of extracellular Ca2into the cytoplasm.

Single, viable taste receptor cells were isolated from the tongue of the guinea pig by enzymatic digestion and mechanical dissociation. The cells could be classified into flask, spindle and intermediate shapes. The intracellular free calcium ion concentrations [(Ca2+)i] of these cells were determined using the Ca2+ sensitive dye fura-2 and digital imaging microscopy. All types of cells produced an irreversible increase in (Ca2+)i upon addition of Ca2+ ionophore ionomycin (1 μM) and denatonium (10 μM). There was no evidence of any increase in (Ca2+)i in the taste receptor cells in nominally Ca2+ free solution, and when stimulated by denatonium (10 μM). When 3 mM CaCl2 was added, the (Ca2+)i remarkably increased. This would suggest that the (Ca2+)i increase in the presence of denatonium mainly depended on calcium influx from the extracellular space. There was no increase in case of high potassium (50 mM and 150 mM) or saccharose (1 mM and 5 mM) stimulation. The hypothesis that the increase in (Ca2+)i controls biochemical mechanisms related to the bitter taste transduction process is worthy of further study.

The effects of putative efferent neurotransmitters on intracellular Ca2+ concentration ([Ca2+]i) in isolated vestibular hair cells (VHCs) of the guinea pig were determined using the Ca2+ sensitive dye Fura-2 and digital imaging microscopy. In the presence of 1 mM acetylcholine (ACh) there was a gradual increase in [Ca2+]i. In the presence of 10 μM ATP there was a rapid rise in [Ca2+]i. Thus, both ACh and ATP seem to be efferent neurotransmitters in VHCs of the guinea pig. When 100 μM Gamma-aminobutyric acid (GABA) was added there was a rapid increase in [Ca2+]i; thus GABA also seems to be an efferent neurotransmitter in VHCs. With the independent addition of 10 μM calcitonin gene-related peptide and 10 μM M- and L-enkephalin there were no significant increase in [Ca2+]i. We presume that these neuropeptides were functioning as efferent neuromodulators rather than as neurotransmitters.

Caloric responses to intracellular calcium homeostasis of vestibular hair cells isolated from the guinea pig were examined. An increase in intracellular free calcium ion concentration ([Ca2+]i) in the isolated cells was observed by direct heat stimulation. The cells, dissociated enzymatically or mechanically, were stimulated by perfusion of solution, in the temperature range of 2.2-5.2°. The [Ca2+]i was analysed using a digital imaging microscope and the Ca2+ sensitive dye, Fura-2. There was an increase in [Ca2+]i in both Types I and II vestibular hair cells with this heat stimulation. The direct thermal influence on vestibular sensory cells is discussed in relation to mechanisms involved in caloric nystagmus.

A driving stress of the Mw5.8 reverse-faulting Awaji Island earthquake (2013), southwest Japan, was investigated using focal mechanism solutions of earthquakes before and after the mainshock. The seismic records from regional high-sensitivity seismic stations were used. Further, the stress tensor inversion method was applied to infer the stress fields in the source region. The results of the stress tensor inversion and the slip tendency analysis revealed that the stress field within the source region deviates from the surrounding area, in which the stress field locally contains a reverse-faulting component with ENE–WSW compression. This local fluctuation in the stress field is key to producing reverse-faulting earthquakes. The existing knowledge on regional-scale stress (tens to hundreds of km) cannot predict the occurrence of the Awaji Island earthquake, emphasizing the importance of estimating local-scale (< tens of km) stress information. It is possible that the local-scale stress heterogeneity has been formed by local tectonic movement, i.e., the formation of flexures in combination with recurring deep aseismic slips. The coseismic Coulomb stress change, induced by the disastrous 1995 Mw6.9 Kobe earthquake, increased along the fault plane of the Awaji Island earthquake; however, the postseismic stress change was negative. We concluded that the gradual stress build-up, due to the interseismic plate locking along the Nankai trough, overcame the postseismic stress reduction in a few years, pushing the Awaji Island earthquake fault over its failure threshold in 2013. The observation that the earthquake occurred in response to the interseismic plate locking has an important implication in terms of seismotectonics in southwest Japan, facilitating further research on the causal relationship between the inland earthquake activity and the Nankai trough earthquake. Furthermore, this study highlighted that the dataset before the mainshock may not have sufficient information to reflect the stress field in the source region due to the lack of earthquakes in that region. This is because the earthquake fault is generally locked prior to the mainshock. Further research is needed for estimating the stress field in the vicinity of an earthquake fault via seismicity before the mainshock alone.

Density perturbations accompanying seismic waves are expected to generate prompt gravity perturbations preceding the arrival of P-waves. Vallée et al. (Science 358:1164–1168, 2017, https://doi.org/10.1126/science.aao0746) reported the detection of such pre-P-wave signals in broadband seismograms during the 2011 Tohoku-oki earthquake. Kimura et al. (Earth Planets Space 71:27, 2019, https://doi.org/10.1186/s40623-019-1006-x) considered that their detection involved some uncertain points, including a concern regarding their signal processing procedure. Specifically, to remove the instrumental response, Vallée et al. (2017) applied acausal deconvolution to the seismograms truncated at the P-wave arrivals. Generally, acausal deconvolution produces artifacts at the edge of the time window. However, they did not present quantitative assessment whether the detected signals were artifacts due to the signal processing. To avoid this concern, Kimura et al. (2019) employed another procedure that eliminated acausal processes, resulting in the detection of a pre-P-wave signal with a statistical significance of 7σ in stacked broadband seismograms. Subsequently, Vallée et al. (Earth Planets Space 71:51, 2019, https://doi.org/10.1186/s40623-019-1030-x) commented that the procedure employed by Kimura et al. (2019) for the signal detection was inappropriate because it dismissed the low-frequency components of data. Although we admit the loss of low-frequency components in the data in Kimura et al. (2019), Vallée et al. (2019) have not yet provided a full account of the validity of their own procedure. Here, we assessed the validity of the procedure employed by Vallée et al. (2017) by quantitatively evaluating the magnitude of the acausal artifacts. First, we investigated how the input acceleration waveform, having an ideal signal-like shape, was distorted by their procedure. Their acausal deconvolution indeed generated a large-amplitude terminal artifact; however, it was removed by the causal band-pass filtering performed after the deconvolution and consequently became negligible. Next, we constrained the maximum amplitude of the artifact due to the noise in a seismogram and showed that it was sufficiently small compared to the reported signal amplitudes. These results suggest that the signal waveforms seen after their procedure were not artifacts but were representing the input acceleration with sufficient accuracy. Namely, their procedure well functions as a detection method for pre-P-wave signals. In the context of this validation, we replied to the comments of Vallée et al. (2019). Restoration of the input acceleration from the output of a seismometer using the signal processing procedure employed by Vallée et al. (2017)

Earthquake ruptures cause mass redistribution, which is expected to induce transient gravity perturbations simultaneously at all distances from the source before the arrival of P-waves. A recent research paper reported the detection of such prompt gravity signals from the 2011 Tohoku-Oki earthquake by comparing observed acceleration waveforms and model simulations. The 11 observed waveforms presented in that paper recorded in East Asia shared a similar trend above the background seismic noise and were in good agreement with the simulations. However, the signal detection was less quantitative because the significance of the observed signals was not discussed and the waveforms at other stations in the region were not shown. In this study, similar trends were not observed in most of the data recorded near the stations used in the aforementioned study, suggesting that the reported signals were only local noises. We thus took a different approach to identify the prompt signals. We optimized the multi-channel data recorded by superconducting gravimeters, broadband seismometers, and tiltmeters. Though no signal was identified in the single-trace records, the stacked trace of the broadband seismometer array data in Japan showed a clear signal above the reduced noise level. The signal amplitude was 0.25 nm/s2for an average distance of 987 km from the event hypocenter. This detection was confirmed with a statistical significance of 7σ, where σis the standard deviation of the amplitude of the background noise. This result provided the first constraint on the amplitude of the observed prompt signals and may serve as a reference in the detection of prompt signals in future earthquakes.