Strategies for visco-acoustic waveform inversion in the Laplace-Fourier domain, with application to the Nankai subduction zone

Waveform inversion is a non-linear and ill-posed inverse problem, with the objective of utilizing the full information content of recorded seismic waveforms. A Laplace-Fourier domain implementation allows a natural `multiscale\u27 approach that mitigates the non-linearity and ill-posedness by inverting low-frequency, early arrival data in the initial stages of inversion. High-frequency components, and late arrivals are incorporated at a later stage. This allows the development of robust inversion strategies capable of handling large wide-angle crustal surveys, leading to reliable, high-resolution velocity and attenuation models of crustal structures. I apply waveform inversion to extract a P-wave velocity model of the active megasplay fault system in the seismogenic Nankai subduction zone offshore Japan, using controlled-source Ocean Bottom Seismograph data. The resulting velocity model includes detailed thrust structures, and low velocity zones not previously identified. The connection of large low-velocity zones in the inner and outer wedge suggests a significant distribution of overpressured regions in the vicinity of the megasplay fault, with the potential to strongly influence coseismic rupture propagation. I identify six-fold key strategies for successful waveform inversion; i) the availability of low-frequency and long offset data, ii) a highly accurate starting model, iii) a hierarchical approach in which phase spectra are inverted first, and amplitude information is only incorporated in the final stages, iv) a Laplace-Fourier approach, v) careful preconditioning of the gradient, vi) strategies for source estimation. Chequerboard tests and point-scatter tests demonstrate the resolution and the limitations of the acoustic implementation. I also compare four misfit functionals for optimization, and demonstrate that velocity information may be reliably extracted from phase alone, and that amplitude information is secondary in updating the velocity model. Finally I develop inversion strategies for retrieving both velocity and attenuation models. Cross-talk between these two classes of parameter estimates arises from the lack of parameter scaling in the gradient of the objective function, and primarily affects the attenuation model. I show the cross-talk can be suppressed by the combination of an appropriate attenuation damping parameter, and by the use of smoothing constraints. Initial velocity-only inversions also help in reducing the effects of cross-talk in subsequent velocity-attenuation inversion

Waveform-based simulated annealing of crosshole transmission data: a semi-global method for estimating seismic anisotropy

We successfully apply the semi-global inverse method of simulated annealing to determine the best-fitting 1-D anisotropy model for use in acoustic frequency domain waveform tomography. Our forward problem is based on a numerical solution of the frequency domain acoustic wave equation, and we minimize wavefield phase residuals through random perturbations to a 1-D vertically varying anisotropy profile. Both real and synthetic examples are presented in order to demonstrate and validate the approach. For the real data example, we processed and inverted a cross-borehole data set acquired by Vale Technology Development (Canada) Ltd. in the Eastern Deeps deposit, located in Voisey's Bay, Labrador, Canada. The inversion workflow comprises the full suite of acquisition, data processing, starting model building through traveltime tomography, simulated annealing and finally waveform tomography. Waveform tomography is a high resolution method that requires an accurate starting model. A cycle-skipping issue observed in our initial starting model was hypothesized to be due to an erroneous anisotropy model from traveltime tomography. This motivated the use of simulated annealing as a semi-global method for anisotropy estimation. We initially tested the simulated annealing approach on a synthetic data set based on the Voisey's Bay environment; these tests were successful and led to the application of the simulated annealing approach to the real data set. Similar behaviour was observed in the anisotropy models obtained through traveltime tomography in both the real and synthetic data sets, where simulated annealing produced an anisotropy model which solved the cycle-skipping issue. In the real data example, simulated annealing led to a final model that compares well with the velocities independently estimated from borehole logs. By comparing the calculated ray paths and wave paths, we attributed the failure of anisotropic traveltime tomography to the breakdown of the ray-theoretical approximation in the vicinity of strong velocity discontinuitie

Management of Neonatal Ovarian Cyst

Objective: There is no guideline for the treatment of neonatal ovarian cysts. The present study analyzed our clinical management of such cysts, as well as the results of treatment. Methods: The present study involved 16 patients with neonatal ovarian cysts who had been diagnosed and treated between January 2002 and December 2016. We classified the cysts into two groups based on ultrasonographic images: (1) simple cysts (SCs)—thin-walled, round, or anechoic; (2) complex cysts (CCs), containing fluid-debris level, solid masses, or intracystic septa. We analyzed the clinical characteristics and results in the two groups. Results: Ten of the patients had SCs and six had CCs. Fourteen were diagnosed during the prenatal stages. Of the 10 patients with SCs, eight were managed using observation only, and the cysts spontaneously resolved in all such cases. Six patients had CCs, including one with an SC that had developed into a CC. Eight of the patients underwent surgical treatment, and the surgical methods did not differ in terms of operation time or complication rate. None of the oophorectomy specimens contained any normal ovarian tissue. Conclusion: We operated on all CCs and on SCs more than 40 mm in diameter, while patients with SCs less than 40 mm in diameter were managed using observation only, as were those in whom differential diagnosis was not possible. We must emphasize that percutaneous aspirations are safe, and we recommend transumbilical incisions, because they preserve both esthetics and ovarian function

CRISPR-Cas9システムを用いた味覚受容体発現調節物質のスクリーニング系の開発

Taste recognition mediated by taste receptors is critical for the survival of animals in nature and is an important determinant of nutritional status and quality of life in humans. However, many factors including aging, diabetes, zinc deficiency, infection with influenza or cold viruses, and chemotherapy can trigger dysgeusia, for which a standard treatment has not been established. We here established an engineered strain of medaka (Oryzias latipes) that expresses green fluorescent protein (GFP) from the endogenous taste 1 receptor 3 (T1R3) gene locus with the use of the CRISPR-Cas9 system. This T1R3-GFP knock-in (KI) strain allows direct visualization of expression from this locus by monitoring of GFP fluorescence. The pattern of GFP expression in the T1R3-GFP KI fish thus mimicked that of endogenous T1R3 gene expression. Furthermore, exposure of T1R3-GFP KI medaka to water containing monosodium glutamate or the anticancer agent 5-fluorouracil resulted in an increase or decrease, respectively, in GFP fluorescence intensity, effects that also recapitulated those on T1R3 mRNA abundance. Finally, screening for agents that affect GFP fluorescence intensity in T1R3-GFP KI medaka identified tryptophan as an amino acid that increases T1R3 gene expression. The establishment of this screening system for taste receptor expression in medaka provides a new tool for the development of potential therapeutic agents for dysgeusia

The Short-Stature Homeobox-Containing Gene (shox/SHOX) Is Required for the Regulation of Cell Proliferation and Bone Differentiation in Zebrafish Embryo and Human Mesenchymal Stem Cells

The short-stature homeobox-containing gene (SHOX) was originally discovered as one of genes responsible for idiopathic short-stature syndromes in humans. Previous studies in animal models have shown the evolutionarily conserved link between this gene and skeletal formation in early embryogenesis. Here, we characterized developmental roles of shox/SHOX in zebrafish embryos and human mesenchymal stem cells (hMSCs) using loss-of-function approaches. Morpholino oligo-mediated knockdown of zebrafish shox markedly hindered cell proliferation in the anterior region of the pharyngula embryos, which was accompanied by reduction in the dlx2 expression at mesenchymal core sites for future pharyngeal bones. In addition, the impaired shox expression transiently increased expression levels of skeletal differentiation genes in early larval stage. In cell culture studies, we found that hMSCs expressed SHOX; the siRNA-mediated blockade of SHOX expression significantly blunted cell proliferation in undifferentiated hMSCs but the loss of SHOX expression did augment the expressions of subsets of early osteogenic genes during early osteoblast differentiation. These data suggest that shox/SHOX maintains the population of embryonic bone progenitor cells by keeping its proliferative status and by repressing the onset of early osteogenic gene expression. The current study for the first time shows cellular and developmental responses caused by shox/SHOX deficiency in zebrafish embryos and hMSCs, and it expands our understanding of the role of this gene in early stages of skeletal growth

Copper-Induced Interactions of Caffeic Acid and Sinapic Acid to Generate New Compounds in Artificial Biological Fluid Conditions

Active ingredients may be ingested through foods, and they can cause several interactions in the human body. Although drug–drug or drug–food interactions are evaluated before the approval of medicines, several functional food interactions are not well-documented because of the wide range of possible combinations of interactions. In this study, we examined the chemical reactions between hydroxycinnamic acids (HCAs), a group of polyphenols, and metal ions in artificial gastric juice or artificial intestinal fluid. Caffeic acid (CaA) and sinapic acid (SA) reacted with copper ions under artificial intestinal fluid conditions and produced new compounds. The triple interactions of CaA or SA with iron and copper ions were also examined. Relative to the initial compounds, CaA and SA derivatives produced by condensation exhibited an increased antioxidant and a decreased prooxidant activity. This study revealed a new food ingredient interaction pattern in which new compounds are produced under biological conditions